WinFF is a GUI for the command line video converter, 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. WinFF is open source and cross platform written in Free Pascal and Lazarus. WinFF is published under the GNU public license.
Install WinFF in Ubuntu
sudo apt-get install winff