This is the music video for Again and Again by The Bird and The Bee. The entire video takes place on the desktop of a Mac running OS X Leopard. It was created by Dennis Liu. That link seems to be his portfolio site, but this video is not listed amongst his work. (It should be showcased, as far as I’m concerned. And Apple should send him a fat check.)
Wait for the KILLER call to action at the end, it’s perfect.