I tried your suggested „sudo su apt-get install ffmpeg“, but it comes up with „No passwd entry for user ‚apt-get'“
With my previous attempt of „sudo apt-get install ffmpeg“ it seemed to go further…
Reading package lists… Done
Building dependency tree
Reading state information… Done
Package ffmpeg is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or is only available from another source.
