While many Linux programs can be happily installed from either a pre-compiled package, or downloading source and compiling yourself, this isn't necessarily the case with FFMPEG.
It's found at slashdot
The greater the number, the exponential increase in installation difficulty. My main need was for FFMPEG to accept a wide range of input formats, while outputting H.264 encoded QuickTime (MOV) files. Here's how I achieved this on a Debian Etch server……..
I'm going to assume that you are familiar with using the Linux command prompt, moving between directories, editing text files and have at least some experience compiling programs.
The first thing I would recommend doing is making an addition to your source repository lists