Successful Joint locks have 3 basics.
1. Joint locks are to flow with the persons movement. By flowing with the movement there is no resistance.
2. Know more than one joint lock. Usually when a person resits one joint lock, they put themselves in the position to have another joint lock applied. For example. The resistance to the wrist lock at 2:00 could have been turned into a different lock.
3. Do what was shown in the video, always keep the attempt to lock a joint hidden, by doing something that distracts the person from your true attention which then allows you to follow #1 of going with the flow of the person's movement.
I understand why in a security course that they ask the person to not resist and it's because of the lack of control of the people practicing the joint lock. The more that my partner resists, the more effort I'll put into doing the joint lock and that's not a good thing to do without control. If I think someone is going to resist then I may try to beat that person's resistance with speed or strength and as a result I may accidentally destroy the joint. It would be different if the instructor knows with certainty that the participants have control, but since he has no way of knowing it's just best to play it safe.
The other danger is that sometimes the resistance goes in the wrong direction. There have been times when I had to release my attempt to lock a joint because the student was twisting in a way in which he would have damaged his own joint by trying to escape.