=When=
While using Totem 1.4.3 with the Gstreamer backend on Ubuntu Dapper, I had a non-music non-movie file in the (rather long) playlist.

=What=
When encountering the unplayable file, totem stops my playlist and displays a dialog box that I must interact with before it continues playing (see attached).

=Why this is bad=
From Gnome HIG v2.0:
  Display an error alert when a user-requested operation cannot be sucessfully completed. Present errors caused by operations not requested by the user by another means, unless the error could result in data loss or other serious problems. ...an error encountered in an automated periodic email check would more appropriately report failure with a statusbar message.

This situation seems to fall more into the latter category of errors than the former.  While I /did/ request that GNOME play that song, a fairly typical use-case for totem is the queuing up of large quantities of files to play in sequence.  In this case, it is more appropriate to mark the file as unplayable (maybe with a /!\ icon in the playlist) than to stop the entire playback operation.  At any rate, it's really annoying to queue up some music, and have to come back every 10 minutes when it's found another file it doesn't know how to handle.

=How=
This can happen quite easily if the user drags and drops in a folder of music to play, for instance.