Using Super Mario levels to play music was a new concept to me when I saw this clip. They not only make a Rube Goldberg style level that plays itself, but this one plays a medley of songs using the in game sound effects in conjunction with the audio track. I can't even being to guess how long it took to set this up.
Video games are truly a new medium for artistic expression. It's hard not to believe it when things like this are possible.