Warning there is quite a bit of swearing in the clip below. Watch it with headphones on if you're at work, or watch it at home. It is however well worth watching if only to see the most frustrating game of Super Mario Brothers ever. The levels that he's playing are clearly user created so it's some kind of ROM, a copy of the game played not on a Nintendo but on his computer.
Also is he trying to sound like Christopher Walken or is that just how he always sounds?