The videos themselves are probably soothing to those having trouble asserting themselves, but to me they work against their own point more than they support it. Especially the "dunning-kruger" video, which seemed more about lashing out based on hurt feelings and didn't have anything remotely insightful to say.
It does have one very important to say: most pepole are shit at judging their own ability. So even if you think you're good at something you have to be really careful, because that confidence might just as well come from ignorance as from skill.
It's a very different lesson than the speakere is trying to teach , but that's another issue. The problem there is that the speaker completely fails to realize that both those with good and those with poor debating skills will think the video is talking to them, that they're the supperior ones.
Edit: ...or, like DArtagnan said (I really should finish reading other's posts before I reply to them):
One must be prepared for the reversal of the "dunning-kruger" experience at all times, though. When you're arguing with someone, and you keep "beating" his points - and you keep hearing the same things being said over and over - you must be prepared for the opposite side sharing this experience. If you hear yourself repeating the same argument over and over, then don't you think it's possible the opposing side is experiencing much the same thing?
Übereil