While there is an argument to be made about how much YouTube should cater to advertisers, and what kind of adult content kids should consume, perhaps with supervision, I don't see where commenters are getting dramatic accusations of "puritanical" from. The content is obviously adult, and all YouTube did was label it as such, which gives advertisers the option of avoiding it (again, what advertisers want is assailable and relevant here, but I can't see any moral problem with YouTube simply labeling adult content - that's just useful information).