1: go on your (a) computer equipped with at least a dvd reading drive
2: download Divx, prolly has to be the full version and while you at it download/buy Dr. Divx. (you can find torrents that have both in the same package.)
3: open up Dr. divx and choose extract from movie or something like that.
4: when your done extracting upload to you xbox and put them in a folder somewere and turn on xbmc, if your smart you would have used this to ftp also. And see if they load they should (some videos you have to open twice).
i have to go but i will check back later.