well their is the slightly small way of rendering in WMV which is like this
Video Quality: Best
Audio: Your Preference
Video
Mode: Quality VBR
Format: Windows Media Video 9
Image Size: High def (1280X720)
Pixel AR: 1.000
FPS: 29.970 (NTSC)
Sec per Keyframe: 3
Quality: 97%
the WOTP MEP we did was rendered like this and it came out at 550 mb.. its not bad ... way lower then if i had rendered in AVI but still not great
Then if you want it SUPER small I would talk to BG.... he taught me, but you have to download a whole bunch of stuff first so get that stuff from him