These are fully functional Audio/Video converters. Please
if your favourite software is missing here.
WinFF is a GUI for FFMPEG. WinFF can convert multiple files in multiple formats at one time. You can convert mpeg's, flv's, and mov's, all into avi's all at once. WinFF is available for Windows 95, 98 , ME, NT, XP, VISTA, and Debian, Ubuntu, Redhat based GNU/Linux distributions. WinFF is available in Brazilian Portuguese, Bulgarian, Chinese Traditional, Danish, English, French, German, Greek, Hebrew, Italian, Norwegian, Polish, Portuguese, Russian, Serbian, Slovenian, Spanish and Turkish.
WinFF is open source and WinFF is published under the GNU public license. You can download this software from this link.