The next one is more serious... very beautiful... they are two movements from the piece "Quartet for the End of Time," written and then performed by Olivier Messaien while he was in a WW2 prison camp with scraps of paper he snuck from the prison guards, but anyway, the video is of a live performance of the quartet with an artist throwing paint at the same time. It's very mesmerizing.

Part 1:
Part 2: