uh
why dont you just download the video as an mp4 through keepvid
and then convert that into an mp3
I would except I want the full song, and I assume that isn't the full song in the video.
If you have a mic, just use this site and hold up your mic to your speakers.
I have a headset with a mic attached... it's worth a shot!
EDIT: Nope. I could have kept trying but I don't want to forget up my headset by trying to bring the mic to the speaker.