Convert your videos quickly, easily, and all at once with WinFF & FFmpeg. Winff is a frontend for FFMPEG. It will convert most any video file that FFmpeg will convert. WinFF does multiple files in multiple formats at one time. You can for example convert mpeg's, flv's, and mov's, all into avi's all at once.
You need a fully enabled ffmpeg to make full use if winff.
Ubuntu and Debian Repositories at http://www.winff.org