AVi Files Rendered Uncompressed in Sony Vegas are Hummongous - Why???

This is part of my Camtasia training at http://www.screencastprofits.com My goal: edit AVI files in Vegas, save uncompressed for further work and completion in Camtasia. My problem: the resulting avi files are huge! 1 minute video = 2.5 gigs!! My flip only has a memory of 2 gigs! And that's for 60 minutes of recording. This video clip is only 7 megs. Yet a 12 second clip in it was almost half a gig before production in Camtasia. So what is going here??? What am I missing? Do bytes mysteriously multiply?