It depends on resolution you make a video + sound + quaility
pc resolution 1366 x 768 ( shit right :P ) , and no sound i dissabeled them , and qulity se for yourself :)
(http://img215.imageshack.us/img215/707/capturetnr.png)
but i belive wont need it any more , gues i will use 1 of the recommendations of these guys
Thank You :)
EDIT : Dont listen them, listen me! ;D
Go to Windows Live Movie Maker (only Windows 7) and just save the video, and it will be 20-30 MB!
lol dude i tryed and the file was 300 mb on fraps with wlmm went to 22 mb :xD thanx alot :)