Comment 2 for bug 1325166

In the "failed to create proxy clip" there is a "show log" button. What happens when you click it?
Or is the problem that nothing happens and no error message appears?

If the message tells you "Unrecognized option 'deinterlace'." you have found Bug
#1389093. If it complains you have no MP3 support you will have to install every package beginning with "libav" and ending with "-extra" instead.
In this case the bug report could be changed into a feature request that automagically offers to install the right packages or requests the user to do so. But I have no idea how this might be archived: The background in this case is that decoding MP3 files might be encumbered by patents in some countries.

Kind regards,
   Gunter.