[Paladin2]

" Sign in to confirm your age This video may be inappropriate for some users. "

WTF is that?

[EEGator]

LOL, there might be heavy drug use and strippers. No nudity

[DiogenesLamp]

" Sign in to confirm your age This video may be inappropriate for some users. "

WTF is that?

It's a tactic that Google/YouTube uses to partially censor videos they want to restrict. By making people "log in" to view it, they convince a lot of people not to bother.

This article explains their various methods pretty well.

https://hubpages.com/technology/The-Methods-and-Layers-of-Censorship-on-YouTube