It seems that the app-install-data package is terribly outdated in Ubuntu
causing 'fun' bugs in Kubuntu ( pretty sure that Ubuntu will have the exact
same issue ) where the media player tries to install gstreamer codecs but goes
bust since app-install-data says that the codec is provided by a package that
doesn't exist in trusty (gstreamer0.10-ffmpeg).
The other impact of this is that new applications were most likely uploaded to
Trusty but their desktop files have not been mined for data and hence do not
appear in the Ubuntu Software Center or Muon Discover.
I emailed the maintainer of the package 2 days ago, but haven't heard back
and was wondering if someone could update app-install-data, or post
instructions on how to do it.