HTTPS Everywhere causes presto.fm not to work after having been enabled during browsing session
The website presto.fm lets you "stream" music of your preference using YouTube as its player medium. This works even if you don't have an account with them, so give it a try here. You'll have to anyway, to verify this bug, so go right ahead.
I've come across a really bizarre bug when it comes to HTTPS Everywhere and presto.fm. If you, at any point during your browser session have had HTTPS Everywhere enabled, presto.fm won't work properly. Even if you never even visited presto.fm during this enabling and disabling. Presto.fm only ever works if you start your browser with HTTPS Everywhere disabled (i.e. you turned it off before you closed your previous browser session) and leave it disabled for the duration of your presto.fm experience.
By the way, just so we're clear on what doesn't work when it isn't working: The Prev, Pause and Next buttons do not work, nor does automatically skipping to the next song after the current song is done. Basically, it's as though presto.fm loses its ability to communicate with the YouTube player due to HTTPS Everywhere.
An interesting and slightly different behavior happens if you enable HTTPS Everywhere while you're listening to presto.fm but you're not on the presto.fm tab in your browser when you do this. This causes the YouTube player to start giving you error messages, but at least presto.fm hasn't fully lost its ability to communicate with it at this point. Refresh, though, and the main bug occurs.
I should also point out that in order to make sure it was HTTPS Everywhere, I disabled all my other add-ons while testing this behavior out, so I'm 99% certain this is a HTTPS Everywhere problem. My browser is Firefox 19.0.2.
As I don't want to browse without HTTPS Everywhere, I've taken to using presto.fm in a separate browser for the time being, but I'd really like to get back to using just one.