Re: YouTube: Kanaya Hirotaka Shihan
I'm reminded of the story about O-Sensei doing a demo and choosing a high-ranked student to be uke, and that student deciding that attacking sincerely meant attacking full-force, with everything he had. The result being that O-Sensei had to do his techniques for real, and he later bawled the uke out because he wasn't able to show things the way he wanted to show them.
So even O-Sensei, apparently, was interested in showing aspects of his art which were hard or impossible to see in a (more) real self-defense situation. The attacks had to be dialed back a bit in order for him to show them.
Which suggests that in demos like the one in the OP, we shouldn't just be looking for street-fighting level of self defense. If the teacher is actually trying to show something, perhaps some level of collusion is necessary--even if the 'collusion' is just an agreement that the attacks will be less than full-on.