Oh god i just noticed nightly has little loudspeaker icons for tabs which have sound running! And they can be clicked and silenced! Im so excited! I just spent like 5 minutes opening videos in new tabs and muting/unmuting them! Best feature ever!!!
Naturally I had to check this out for myself. Launched and updated Nightly (Firefox 42) then opened YouTube and tried to play a video…nada. Odd, I couldn’t get YouTube to work. Then I noticed the familiar overlay that Flashblock uses. Hmm that’s odd, could’ve sworn I had YouTube whitelisted (turns out I did). So then I clicked on the Flashblock button and the video played, but no speaker on the tab. Since this is not the first time lately I’ve had issues with Flashblock on a site that has been whitelisted, I decided I would disable the add-on and see if that makes a difference. After restarting Nightly went back to YouTube and played a video and this time I had the speaker icon.
Now, this is where Firefox’s version is improved. If you click on the speaker on the tab, you can mute (or unmute) the audio without even having to switch to the tab. Chrome only has an indicator that there is audio playing in the tab, but no mechanism to mute (or unmute) the audio playing in said tab.
Firefox 42 is scheduled for release on November 3, 2015. It appears this feature was just landed in today’s (or tonight’s) nightly builds. This feature was requested in Bug 486262 on March 31, 2009.