This is by far my favorite hair tie; I'm not aware of any technique which is more secure while still pulling the hair evenly and with minimal damage, and compared to other techniques with a similar approach, I find this one much easier to tie (and to learn).

As you can see, you don't need someone with super long hair for this tie to work -- in fact I've tied it successfully on hair significantly shorter than Rachel's is in the video. Depending how clean, straight, and slippery someone's hair is, the minimum hair length you can get a solid tie on will vary; but it's possible to get a good grip even on hair that's only long enough to gather from a small portion of the head, if you use narrow diameter rope.

Speaking of rope choice, while narrow, rough rope (like hemp and jute) will grip hair best, it's also important for this type of tie that the rope be supple. I had a particular spool of 3mm hemp that was very rough and you'd think would work great for hair ties, but was actually awful, because it was extremely tight-wound and springy. In rope that isn't sufficiently supple, the half hitches in this tie will tend to start opening up as soon as tension on the rope is released.

Finally, the most important factor in succeeding at this tie is to watch your tension; keep the rope very tight the whole time, and make sure you're not letting a big gap open up between the tie and the scalp, which wastes valuable length when tying on short hair.