Prior to v57 I could click on a link like http://freezone.iinet.net.au/include/radio/playlists/2.m3u and tell Firefox to always open it in VLC, after which I would be able to listen to these sorts of streaming music stations in VLC with a simple click in Firefox. It did open a blank tab as well, but no big deal. Now when I click such a link, a new blank tab still opens but it just sits there in a "loading" state with a status bar message "Connecting to iinet.net.au...". Eventually it times out. This has occurred on 2 different machines running Linux Mint (with Firefox Sync active) but also on a Windows 7 machine which does not have FF Sync enabled. The problem persists even in Safe Mode (i.e., with extensions disabled). There are ways around this for me - like loading the URL directly into VLC, though that is clumsier; I'm at a bit of a loss as to why/how this change has occurred. But it seems like Firefox wants to play mp3 audio in its own (html5?) builtin player, but that it doesn't support m3u. The reason I would prefer to listen to streams in VLC is so that if I close Firefox after starting a music stream, then VLC can still keep playing the music.