http://www.youtube.com/watch?v=8UzoVih4ZBU
FIA GT3 @ Silverstone 2011 (MT89Motorsport had better quality, but the account got taken down, and the replacement account doesn't have this one back up).
There was also a pretty good GT1 video from the same round, but that video also got taken down with the account
Edit: Here's some footage of the cars rolling out for their warmup lap at yesterday's GT3 race at Zandvoort
www.youtube.com/watch?v=CKBZBgms0og