There is a collection of free mac video converters to help mac users to handle nearly any file format.
1. MPEG Streamclip
MPEG Streamclip is a powerful free video converter, player, editor for Mac and Windows. It can play many movie files, not only MPEGs; it can convert MPEG files between muxed/demuxed formats for authoring; it can encode movies to many formats, including iPod; it can cut, trim and join movies. MPEG Streamclip can also download videos from YouTube and Google by entering the page URL.
FLV2iTunes is a simple docklet application for converting movies to iTunes,iPod, and iPhone supported format.You just need to drag and drop movies to it and you just need to wait. It will accept any movies format that are supported by ffmpeg (WMV, XVID, DIVX, FLV, AVI, and more), converts it, and insert the movie into iTunes library.
HandBrake is an open-source, GPL-licensed, multiplatform, multithreaded video transcoder, available for MacOS X, Linux and Windows.
Any DVD-like source: VIDEO_TS folder, DVD image or real DVD (unencrypted–protection methods including CSS are not supported internally and must be handled externally with third-party software and libraries), and some .VOB and .TS files
Most any multimedia file it can get libavformat to read and libavcodec to decode.