@dale It's really useful, especially after restoring a session with hundreds of tabs and something starts randomly playing in the background.I do think safari's take on it is slightly friendlier from the UX perspective. Basically if any tab is playing it shows a speaker in the url bar (next to translate and refresh). Clicking on it mutes all tabs, but what I find more useful is right-click will list all tabs that are currently playing audio, so you can just close the tab itself.