Good to hear it worked for you too.
The av_err2str functions is probably a ffmpeg 2 thing then. I'm using ffmpeg 2.
It was really easy to install on my CentOS using the guide at http://tecadmin.net/install-ffmpeg-on-linux/
The reason i installed ffmpeg 2 was that i hoped that ffmpeg was the cause of my red-screens. Its apparently not, but i've left it there.
The only reason for using av_err2str is to get debug files that writes "Connection failed" instead of -123123 (just as an example).