I'm actually working through this exact problem- I initially found UMovieMaker but I tested that out last night and the files were HUGE 3.8 gigs for a quicktime movie that's less than a minute and a half. This is what I got from Vimeo when I uploaded it:
I found another library: GSVideo, which I'm gonna try out tonight, it has a lot more control over video quality and output format- I'm hoping it'll work for both of us!