Although it is still in beta, ffmpegX is quite a powerful video compression application. It uses 3 UNIX encoders and allows you to encode or re-encode video with such compression algorithms as MPEG-4 (Part 2), DivX3, H.263, H.264 and XviD. The current version as of August 2, 2006, is 0.099w r5 and is in Universal Binary.
Since ffmpegX relies on UNIX encoders, you must install them in Library folder in the System before you actually encode video. If you had a non-Universal version of ffmpegX and are now trying to use a Universal version, note that you cannot use old UNIX encoders because they must also be in Universal binaries.
The strength of ffmpegX is its access to MPEG-4 functions. Depending on which encoder (ffmpeg, mencoder or mpeg2enc) you use, you can enable or disable MPEG-4 functions including 4-motion vectors, Trellis quantization, Quarter pixel and so forth.
Click on the button to download UNIX encoders. (Universal Binary)