I find it an interesting question because:
A) Not every video branded as culturally unacceptable will be. Not every video is as bad as the worst-case hypothetical used to justify the content classification.
The landscape of cultural attitudes differ from California-based content minders. The categorization can be flat out wrong, there will undoubtedly be a small percentage of videos that even the minders see as mis-classified.
B) Social interventionist policies can - and often do - backfire.
e.g.: Teens that deliberately seek out taboo. The allure of R movies, M games, Explicit Lyrics, and underage binge drinking can cause them to live a period of their life less well-adjusted than if that content wasn't aggressively filtered from their lives in the first place.