Last month ffmpeg released another update for the 2.2.x branch, 2.2.15, with tons of updates and fixes compared to the 2.2.2 that’s hosted here. It’d be cool if the new one was hosted. I’m working on building it, but it can be quite a pain to build.
Audacity does not ship or host FFmpeg. The site we recommend for FFmpeg is not affiliated with Audacity.
Audacity won’t work with FFmpeg that has more updates than the 2.2.3 release of June 2014. That is that latest you can use with Audacity, as far as I know, unless of course you patch Audacity yourself. We have no plans to update Audacity support for FFmpeg in the near future.