Below is a link for one of my favorite music videos going at the moment, i wont ruin the surprise but if you watch it for the first few seconds you think it is pretty average and then they pull off some nice effects and i was wondering how they did it.

http://www.youtube.com/watch?v=n1wnOUH2jk8

It is also not a bad song.

from an inexperienced eye, I do not think it was green screen. the shadows appear correct for the angles of the riders, and also, the shadows of the riders landed on other riders. if it was done with green screen, it was shot with all of the outriders at once, not one at a time. in my opinion, it was filmed that way, with several takes.

Looks to be a composite, you can see the road 'jump' in values when they merge behind her - really well done though. Nice images, good song.