Knots or nuts?

So I had heard about this and found it on youtube. I personally think it would be really cool to learn this art, although I don't know how much I would trust a knot compared to a nut.

So the question is has anybody used knots to protect a climb?

https://www.youtube.com/watch?v=QQstfpiYu_A

I did it a few times on easy mixed routes. I didnt have gear but wanted to climb the route and had read about it. If your knots to construction ratio is right its a blast. And I even hung on one just to see how it would set.. and it was pretty hard to get back out.

Never used them myself but have found them on a few old routes in the Red Rocks and they do make things a bit spicy. That said, if you are on the sharp end and suddenly realize you are about to run out of static protection and have nothing else, a jammed knot will suffice. The ones I have seen were always frost knots in tubular webbing, which allow far more contact in a crack than rope, perlon, or kevlar because more of the surface is in direct contact with the rock. The rule is - Just don't fall.

Sure, for anyone who´s been climbing for more than about 40 years they were common practice. I bolted a sport route using one as a re-belay last week and it survived my considerable weight jugging twice no problem.