Saltwater (Original Mix) by Chicane with iTunes visualizer
SEIZURE WARNING! Bright flashing lights.
Original mix of Saltwater by Chicane featuring Maire Brennan of Clannad, from the album Saltwater - EP. Awesome track.
The visualizer in the video is called Jelly, and comes free with iTunes version 8.0 (at least, I'm pretty sure it's free).
Enjoy!