Hong Kong Protests: the dark, silent (and hidden) side of Hong Kongers [video]

If YouTube asks "Sign in to confirm your age", here is an embedded version which doesn't require sign in:

https://www.reddit.com/r/Hong_Kong/comments/de4a7s/hong_kong...

Why does YouTube do this? Allow embedded media on Twitter and other websites to play without restriction, but when you try to watch with YouTube, permissions are enforced?