Snake game in Youtube movies

Ever watched a boring youtube movie?
Want something more? Maybe funny?

There it is! Select any movie from gaming category, and while the movie is playing (not paused), keep pressed for few seconds UP and LEFT keys simultaneously.

Snake appears and you can play the game WHILE the movie is still displayed in background, and even after the movie ends.

Later Edit: apparently, the game can be played in movies from all categories, even if only LEFT key is long pressed. The only restriction is that the movie player must be the new one (hint: volume slider is horizontal, not vertical).