Double rope rappel question

This may be a dumb question or it may not be but it's boggling my inexperienced mind a bit so I'm turning to you more experienced climbers for a quick answer hopefully.
I watched a video off of rockandice.com from the link here on mp and in it one of the guys is rappelling off what looks like two ropes, a red rope and a green/yellow rope, but he is only using the red rope to rappel with a grigri and the other rope looks like it's tied to his harness with a figure 8 follow through as he comes down. Im not real experienced with double rope rappells yet and the way I know of is both ropes tied together at the rappel anchors with the knot on on side of the chains or whatever your rapping of off. I know of ways to single and double rope rappel this way, but the way he is rappelling in the video confuses me. Can someone explain how this is set up as a different way to rappel or if I'm confusing it for something it's not. I'll attach the link but to save time the part I'm referring to is at 9:29-9:36 in the video.

vimeo.com/m/33613956

I tried searching for other posts that could clarify this but didn't find much. If my question confuses anyone just let me know. Thanks

Are you sure his second strand was a rope and not a light tag line? Some people carry a rope-length of 7mm cord I've heard, then rig a rappel where they drop both but only weight the rope. Then when they are at the bottom they use the light line to pull the rope.

He also could be doing the same thing with two full strength ropes, but only rapping on one because he only has a grigri.

The way this is set up at the top varies, I think, but I *think* it usually involves a stopper knot or carabiner-as-slip-knot deal.

Don't go taking my word for it though. I haven't tried any of this and my info is all secondhand.

That's the thing I'm not sure if one rope is set up for rappel and the other a tag line or if it's some other set up. I saw the end of the Yellow and green rope tied to him and didnt know if it was part of his actual rappel line off two ropes somehow. Like I said I have only little experience using two ropes and I fully intend on using the method I know is safe that I'm comfortable with I just want to figure this out for future knowledge.
As for the idea of it being a tag line set up, you could be right. I've never done this set up either so I'm not real sure but I get the concept of how it works.

Ok so I've been all OCD about this situation quite a bit trying to think of an answer before someone else can explain it to me. I tend to get that way when something stumps me, I dont know why and I hate it, but anyways. After a few shots of whiskey and some brain storming I came up with a possible theory but I'm not sure if it's practical or ever been tried in climbing/rappelling situations so feel free to confirm or deny this idea:
The climber is at his rappel station with both ropes, the end of one rope tied to the other rope with a figure 8 or a triple fishermans knot (the two ways I've heard to use in this situation). Let's say the rope is fed through chains and the knot is on the right side of the chains since it fits my theory based on the video I'm talking about. The other end of the rope on the left (or the yellow and green rope which corresponds to the video) is tied to the climbers harness with a figure 8 follow through knot. Now keeping in mind the rope going through the chains with the knot on the right side of the chains, the climber would drop all the rope down the route, all but the small section attached to him and what's through the chains and what he can reach below him so he is at the end on the rope. The climber then attaches his grigri to the hanging rope on the right side of the chains which would be yellow and green at this point.
The climber starts to descend down the mountain using only the yellow and green rope until he comes to the point where the two ropes meet at the knot. Hopefully, based on my theory, at this point the climber is at another belay or rappel station with anchors, or he could set up his own anchors with some gear. At this anchor point the climber would tie himself off and adjust the grigri so it's underneath the knot joining the two ropes together. At this point he would be using the red rope in the video.
After doing this the climber would continue rappelling down the mountain until he reaches the bottom or reaches the end of the red rope. For the sake of this message and my main question let's say it's the bottom of the route.
Once at the bottom the climber could undo the grigri as well as the knot from the yellow and green rope on his harness and pull the rope down from the red rope since the descent would have pulled the central knot up equalizing the lengths of the rope keeping the knot on the right side of the anchor chains.
This theory I came up with would explain what I believe I saw in the video. As I've stated before I'm not very experienced in two rope descents so I may be way off here but it's all I could come up with just to ease my obsessive mind so I can get some sleep. I don't know if this technique is even used or safe for that matter since it puts alot of stress on the knot once your on the lower rope. Hopefully my description was clear enough to give you all a mental picture of what I was thinking. Feel free give me input on my wacky rappel idea also.

http://www.traditionalmountaineering.org/FAQ_ReepschnurRappels.htm

look at the red rope set up around 9:42. it seems to me that they are fixing a single rope rap for the first person who then can get started down to the next station while the second line is tagged to their harness. (in other words, they fix the end of the line they are pulling to the anchor, as the 2nd pulls the line down the 1st gets on rappel, as the knot comes to them, the first tags the other rope (green/yellow) to his harness so as he begins rappeling on the fixed 1st line he pulls the second line with him...as the first person goes off rappel, the second person (who has been holding onto the 2nd rope as it gets pulled by the first rappeller) turns it into a double rope setup and heads down also.

however, it doesn't quite seem to be happening that way in the movie. Also the first rappel they show, he is rapping a single fixed line while his partner is already down and coiling a blue rope...and the last one they show, there are 2 ends of red rope hanging, a line of green, and he is single rope rapping

i must say, i think i may be stumped too

i don't think it is a reepschnur because the rope is tied into his harness and taught...plus they do not have any skinny ropes, all their ropes look at least 9.8

p.s. check out the double overhand knot (euro death knot), best way to tie your ropes together. quick 'n dirty

Parker beat me to it...I thought the fig 8 was possibly kept tight just so the ropes don't blow all over the mountain snagging in a flake and causing an epic. His partner might be paying out slack to him.

Garrett you pretty much wrote what i wanted to tell you last night, without wanting to write all that. You wouldn't need another rappel anchor or midpoint anchor though, as you can bypass a knot with a few different methods to move your rappel device below the knot then keep rappeling. I didn't actually watch the video just read what you originally asked. It would work fine though its going to wear the shit out of the rappel anchors with near 200 feet of rope running through them. There's definitely a name for that method but idk it. There are other ways also to rappel on one cord as well. I'm not even going to try and figure out what Parker said, sounds like a clusterfuckkk.

FrankPS thanks for that link it actually showed me some good stuff. Helped me figure some things out that I wasn't positive on. However I don't think it's the method used in the video im talking about.
ParkerKempf, I think I get what you explained but that, to me anyways, sounds complicated. It could work but again it doesn't look like this specific situation. And I'm glad its got someone else besides me stumped! I dont feel so bad now. Thanks for the tip on the double overhand I'll for sure do some practicing at home using that knot until I figure it out fully.
Mikebest, what you said about his partner paying out slack to him, do you mean he is using one rope (the red rope) as a single fixed rope to rappel from and the other rope tied to him (green and yellow rope) is being used by his partner who is above him to be a second belay to control his descent? This definitely would work but seems like it would take extra time (not a bad thing in some cases)
Fat cow, I'm glad someone else had the same idea as me since I wasn't real sure of it being an actual method to use. But I do agree it would wear out anchor points really fast if done a lot. And I'm glad you pointed out getting around a knot without the use of another anchor point. I forgot about that in my late night rant. I'm aware of it's possibilities I just spaced out I suppose.
Thanks everyone I do appreciate all the info. I am still stumped by the main question I have from the video so feel free to keep more ideas coming my way!

Garrett Wilson wrote:FrankPS thanks for that link it actually showed me some good stuff. Helped me figure some things out that I wasn't positive on. However I don't think it's the method used in the video im talking about. ParkerKempf, I think I get what you explained but that, to me anyways, sounds complicated. It could work but again it doesn't look like this specific situation. And I'm glad its got someone else besides me stumped! I dont feel so bad now. Thanks for the tip on the double overhand I'll for sure do some practicing at home using that knot until I figure it out fully. Mikebest, what you said about his partner paying out slack to him, do you mean he is using one rope (the red rope) as a single fixed rope to rappel from and the other rope tied to him (green and yellow rope) is being used by his partner who is above him to be a second belay to control his descent? This definitely would work but seems like it would take extra time (not a bad thing in some cases) Fat cow, I'm glad someone else had the same idea as me since I wasn't real sure of it being an actual method to use. But I do agree it would wear out anchor points really fast if done a lot. And I'm glad you pointed out getting around a knot without the use of another anchor point. I forgot about that in my late night rant. I'm aware of it's possibilities I just spaced out I suppose. Thanks everyone I do appreciate all the info. I am still stumped by the main question I have from the video so feel free to keep more ideas coming my way!

I'd doubt his partner is lowering him from the top as a back up to the rappell, two guys climbing a 5.12c big wall are probably beyond that level of redundancy, plus they appear to be rappelling off bolts, so probably less concerned about their anchor.

Effectively they're using (link below) this method which is pretty commonly used these days where you need full length rappels but want to either A. Use a skinny cord instead of climbing with doubles or B. want to rappell with a gri gri.

rockandice.com/articles/how…

What I'm saying is that as he's rappelling down his partner is feeding the rope (in a pile hand over hand probably) from the top to him to avoid tossing the cord down and having it snag over what appears to be some potentially chossy terrain with lots of flakes and snag potential. Great video regardless

Thanks Mike that does make a lot more sense to me now. Im sure that's the likely case in the video. Now I can stop thinking about it so much! Haha.
Yes it is a great video!