This codec is handy for playing a number of file types with Quicktime that the DivX codec cannot handle. These include MS-MPEG4v1 and MS-MPEG4v2 encoded movies. It can also play XviD, DivX 3.11, DivX 4 and DivX 5 encoded files but since it lacks an audio parser like that of the DivX codec, it requires that any .avi file containing mp3 audio be converted to a .mov file using DivX Doctor before sound can be played. I would therefore recommend having the DivX codec installed to play back those file types. The DivX codec overrides FFusion if both codecs are installed and the decoding capabilities of the FFusion codec are only invoked when a file with video encoded by a codec the DivX cannot handle is opened. This version of the FFusion codec is fully compatible with Front Row.

On PPC machines FFusion is the fastest Quicktime decoder available for many file types. This is useful on slower machines that would otherwise play back high bitrate movies with stuttering or jerky picture. The Intel version of ffusion is much slower at decoding video than the PPC version working under Rosetta. It is also slower than the Universal binary of the DivX codec for file types that both can handle.

With both this codec and the DivX codec installed there are very few movie file types in .avi, .mov or .mp4 containers that Quicktime cannot open. The DivX codec would decode DivX 3.11, 4, 5 and Xvid movies, the Apple MPEG-4 codec would handle MPEG-4 and 3ivX 4.5.1 encoded movies whereas FFusion would decode MS-MPEGv1&2 encoded movies and any movie that has been converted to a .mov file with DivX Doctor.