"There is no striking allowed in this practice, "
If you are going to do anything worth while in the way of knife defense, striking has to be the essential component.
As for the video, I have no idea what is being taught... The guy with the knife is being taught to hesitate and be defensive when, in fact, he has the advantage of holding the deadly weapon. He should be initiating.
The "attackers" are basically being taught to sacrifice themselves by swarming the knife holder, seemingly on the assumption that they can over whelm him before he can kill them all. Probably true but a bit kami kaze for my taste.
This just isn't good training no matter how you look at it. What is being imprinted with this exercise is all the wrong stuff.
As Bodhidharma once said, "No merit!"