Well, I dont know much about it myself, but I can help you with recording. If you want a simple, half-size (or if your willing to pay, full size) movie of gameplay, use Fraps. Then look for a video and music editor. combine what you want, add some music, and there ya go. Posting it: I have no clue. look for soemone with FTP space.
Download FRAPS and Windows Media Encoder for starters. Capture it with FRAPS, edit it with Windows Movie Maker(included with XP) and encode with WME to get the file size down. There's fancier programs out there to do each step with, but I find those to be the most user-friendly.