The issue is worth discussing. The reason the file size in huge is that most P4's can't compress too much in realtime. So a small compression is done, but that's it.

If you are lucky, the file is in AVI or MPEG and you can use VIRTUAL DUB to recompress the file you want with some DiVX CODEC.

I will not teach you about codecs and Virtual Dub since both have fine web page documentation. Light codec learning is over at http://www.moviecodec.com

Bob