possible to shrink recorded video files?

I just got finished recording and converting 77 files from youtube and was gonna try and piece them all together (in sections, not all at once). I suddenly came to the cruel realization that these files are HUGE!!! A 4 and a half minute video is almost 65MB. I can't realistically piece any substantial string of them together without having a video thats 20+ gigs.

All these files are already saved in .mpeg format... all 77 of them. Whadoido?!? :confused:

Try at:

http://www.clipconverter.cc