It's pretty easy to do it in a way that makes the knot about 3 feet up the rope, which is what you need if you're about to tie in. The way this guy does it is useless for climbers because the knot forms too close to the end of the rope.
Ryan Williams wrote:To add: The way I do it is also useless. It's a bar trick. Can you clip a clove hitch or munter to a biner with one hand? Tie a bowline? Much more useful.
Agreed, one handed munters and cloves are very useful, unlike this one. I just thought it looked pretty damn cool.