Hi,

I've been experimenting on using the authoring tool with various installations of Linux. The ffmpeg install seems to cause issues depending on the version of Ubuntu you are on. For reference, the below will ensure it installs/works regardless of your Ubuntu version (12 upwards). 

sudo add-apt-repository ppa:jon-severinsson/ffmpeg
sudo apt-get update
sudo apt-get install ffmpeg
sudo apt-get install frei0r-plugins