I use a freeware program called prism video converter....ihad to convert my camera videos not so long ago to enter into the proj jump competition. It converts files to wmv, asf, mpg, 3gp, mp4, mov, fvl. It'squite fast and is very easy to use.
Another one to use is the youtube downloader....the version i allows u to download files from youtube nd then convert them into other formats...so u could skip the downloading part nd just usethe converter....wokrs really well....
gd luck