What is FFmpeg

FFmpeg is a trademark of Fabrice Bellard, originator of the FFmpeg project.
FFmpeg is a complete solution to convert audio and video based on libavcodec - the leading audio and video codec library.
FFmpeg is free software licensed under the LGPL or GPL depending on your choice of configuration/compile options.
More info can be found here.

FFmpeg binary. Say what?

Without FFmpeg installed, iFFmpeg operates as a comprehensive information tool for retrieving extended technical information of media files.
iFFmpeg also acts as a frontend for FFmpeg which means it needs a working FFmpeg binary. Without this binary, several iFFmpeg features aren't doing anything.
There are common ways to get hold of a working FFmpeg binary.
You can compile it yourself and although it takes some steps to master it is very rewarding to compile your own custom made FFmpeg binary.
Ones you master this it is easy to compile the latest version.
For more info compiling your own binary do some Googling with keywords like 'ffmpeg', 'binary', ‘OSX’.
Some good links for compiling your own : here and here
Another way is to download a ready compiled FFmpeg binary. There are several places that offer daily compiled binaries. A good place to start is here or here
We advice to only use static build FFmpeg binaries.

Why do we not distribute a FFmpeg binary?

iFFmpeg has a feature-set for operating the open source FFmpeg without the need to type long command lines. Graphical controls are sent programmatically to such external components developed by third parties and running outside the iFFmpeg application
In order to comply with applicable laws and licenses which may vary from country to country, no FFmpeg binary is included.
More info can be found here.