This is a perfect example of "you can't please everyone!" Having background tabs wait to play videos until activated only became the default in Firefox 56 after many requests.

To switch it back to the old setting:

(1) In a new tab, type or paste about:config in the address bar and press Enter/Return. Click the button accepting the risk.

(2) In the search box above the list, type or paste autoplay and pause while the list is filtered

(3) Double-click the media.block-autoplay-until-in-foreground preference to switch the value from true to false

Success? And sorry for the inconvenience!

Thank you, it worked. A few comments however: getting a lot of requests for something doesn't mean it's the majority preference, obviously the people who are content will not be posting "hey, this particular feature is a-okay the way it is". That being said, given that it's not a bug like I thought but an actual design choice, it's no big deal. But! Why is the option to restore normal functionality hidden along with most of the options? Even if this hidden options list in about:config was just a series of extremely technical choices wouldn't it make sense to include all of them in the options under a tag labelled "advanced"? You know, so people who are specifically looking for something that actually exists could find it rather than thinking their browser is buggy? (Not complaining, this is a sincere question.)

Thanks again.

I find this hard to answer... The user interface people do not want a long list on the Options page; on the contrary, they prefer to simplify it. That said, most of the Options page was designed 10 years ago before media was so important, so a proposal to add a Media section might be worth submitting.

Since UI changes take months to years, we probably need to have a help article people can find more easily.

Thank you for the answer.