For the record, Doc is a real lawyer, and I would trust him to make any informed legal decision/clarification on this board more than anyone else.
Personally, I think that is more of a video about why little kids should not be allowed to have video cameras. Yes, the kids look goofy as hell, and listen to crappy music. However, during their "war" they were wearing eye protection, and even though they thought their springers were going over 200 fps, they were not. Therefore, what real "danger" were they in? Yes, it was foolish to mess around in their front yard (probably would have been smarter to do it in the back), but it seems to me that after some OFFICIAL AA games, some ballsy folk ("Adults"), engage in pistol duel/draw contests with GAS pistols going above 300 FPS.
The point is, there is not enough context to make an informed decision about their true maturity level. Granted, I think they are idiots, but watching a sub five minute clip of someone messing around with his friends is far from sufficient to make an accurate judgment of their character or maturity level.