That depends greatly on what format the original clip is, and
what software you have access to. Hopefully you have AfterEffects
CS3. You can render the original clip from AfterEffects as an flv,
and decrease the physical dimensions of the clip, the frame rate,
and the bitrate. Just from personal experiences, I'd say you could
cut the 100M down to probably about 60M.......maybe a little more.
If you have AfterEffects, just play with the settings and see what
you can come up with. If you don't have AfterEffects or Premier
then there really is nothing you can do that I know of.