Installing ffmpeg on Mac OS X - fluent-ffmpeg/node-fluent-ffmpeg GitHub Wiki
Using Homebrew
The simplest way to install ffmpeg on Mac OS X is with Homebrew.
Once you have Homebrew installed install ffmpeg from the Terminal with the following:
brew install ffmpeg
You're done!
Homebrew installs ffmpeg with many of the common codecs including H.264.
BEWARE: On OSX this blew away Python2 version in /usr/local and installed Python3.