Simon,
Do you get this error when you first start Capture?
If yes, try updating/installing latest QuickTime..
http://www.apple.com/quicktime/download/
I had a similar problem which was resolved by this. Quicktime seems to be required for the new video support..
Pleased to see the video support, but shame it requires quicktime :-(
If this is your problem, Lar's can you not make the installer check for quicktime, or at least provide a more friendly error from Capture?!?
Hope this helps,
Paul