Comment 7 for bug 977866

Further investigation reveals that Rhythmbox can play flacs via a samba share but not mp3s (sounds crazy, but I've triple checked!)

Totem can play both only if the ~/.gvfs fuse filesystem is mounted. Today, the gvfs-fuse-daemon process had crashed (or otherwise stopped for some reason) and totem was having the same problem as rhythmbox (playing the first second or two of mp3s). When I remounted .gvfs totem was able to play mp3s (though rhythmbox still could not).

So this is not fixed, but there are some more hints about the problem there and this bug is beyond just rhythmbox.