I do have stressed this move against a much stronger and bigger opponent assumin i was the weaker girl.
If you have made this drill by yourself instead of came here so diligently pointing the flaws of what you have saw just on the vid you will end up realizing all the move is real. Besides that i agree only with that if the guy really grabs hard it will very hard to release the hand as showned in the vid.
But anyways he will fall and lost balance when you transition to zenkutsu coz hes not expecting that. I havent told the guy i was about to do this just told its a karate drill and that he have to grab hard both of my wrists.
Now hes on the ground prone to get his head kicked while you still up there. Maybe you need a video footage of that also?
I'm sorry but I am that weaker girl and I did just try this out to see what would happen and DaveB is correct, it doesn't work. I'm not speculating on this, I tried it out with a couple of guys, as self defence it doesn't work.