This is something interesting. Youtube has some hidden code on their website that when activated, you can play a game of snake while watching the video. This is something not announced (yet) and seems to me like the Pacman that Google has introduced (although Pacman is quite official).
To play this game:
Go to Youtube website (embedded youtube video is not possible).
- Press pause on the video
- Press Left Arrow key and hold
- Enjoy the game. (you can continue the video by pressing play)
Nice one, Youtube!