If you have Windows XP, there's the XP Codec pack thats free. This is the one I use for videos and I use WMP 9x for playback. File encoding just means the way the file was made. Whats the file extension? DVD files may not play full screen in media players because it might be for wide screen playback. If it's for wide screen, you'll get the letterbox quailty on full screen playback.