The first 48 videos, in case you don't want to watch them one by one. I know 48 isn't a round number, but that's the max number of videos allowed by the editor.
EDIT: I'm seeing a lot of people criticizing this game, saying it wasn't tested properly, etc. That isn't true. These glitches mostly have to be done on purpose, and glitchy areas are mostly out of the way. The game wouldn't nearly be as fun without the glitches, but the main game functions perfectly and the glitches don't make the multiplayer broken, so if anything this game is a testing triumph.
EDIT 2: Turns out there are fifty videos. I guess Youtube's video editor can't count.