I recently noticed some behavior in the Audacious media player that I hadn't seen before.
When playing mp3 files it's creating temp files in home/tc that remain there after you close the app. These temp files then get backed up when you shut down, unless you exclude them from your backup.
Maybe this is some obscure buffering feature or something, but I don't recall seeing it in earlier versions of Audacious (or in any other media player). I fiddled with a couple of settings but that didn't seem to help.