Pandora uses jPlayer to play audio which has an invisible Flash component to play mp3s on browsers that don't support it.
If Firefox requires 'click-to-play' on an on-screen piece of Flash to enable it, all sites using jPlayer to play mp3 simply will not work.
And of course this doesn't just affect jPlayer, many other players use this technique.
Much better -- as mistercow reasons -- to have a pop-up asking you if you wish to run Flash on a particular site and I would love to see an 'always allow' option here.
TL;DR there is a licensing issue with the MP3 decoder. It's more complicated than that, but most of it is due to software patents. http://en.m.wikipedia.org/wiki/MP3#section_10 has more info if you're curious.
If Firefox requires 'click-to-play' on an on-screen piece of Flash to enable it, all sites using jPlayer to play mp3 simply will not work.
And of course this doesn't just affect jPlayer, many other players use this technique.
Much better -- as mistercow reasons -- to have a pop-up asking you if you wish to run Flash on a particular site and I would love to see an 'always allow' option here.