I recommend using fraps. You have to buy it, but there is a free version of it where you can record 30 seconds at a time.
But, you can always get a bootleg version off a torrent. I did this and it works perfectly.
http://thepiratebay.org/tor/4050438/Fra ... _-_TheOneX
Theres the link if you wish to use the torrent for FRAPS. It works perfectly.

Have fun with your music video.