Replying to Freeride/Dirt jumping fun

Picked up a T2i not too long ago, been having a ton of fun with it so far...
I shot this video in a few hours one evening. I'm not completely new to editing, but I'd love some critique and feedback on the video.
Right out of the gate- the sound is a little off which happened after uploading to vimeo. I've had this problem before, can anyone shed any light on it?
Enjoy, and check out my site, www.naturephotograff.com for more cool things.

A Kwik Stop at Skytop ft. Derek Defrees from Nature Photograffer on Vimeo.

Derek and I cruised out to the abandoned quarry for a few hours one evening to put together a video showcasing Derek's hard-charging style. Weeks of drought left the in-runs to most of the jumps a little too dusty to get any good speed, but Derek still found plenty to get after. More to come, www.naturephotograff.com for more updates.

Shot with a Canon T2i/ Tamron 18-50mm /2.8
Song/Artist: Cruddy/Madlib