This is a Lego version of the Michael Jackson video, Thriller. (If you haven't seen the original, it's a classic. Check it out.)
All I can say is that someone had LOTS of free time to do this. This is actually the SHORT version of the video, cut down to where it actually gets more entertaining. The original is over 10 minutes long and is shot for shot the entire Thriller video made out of Lego people.