Microsoft recently announced that the Edge browser will start blocking auto-playing media starting this Fall with Windows 10 Redstone 5 update. Firefox is now the third major browser after Chrome and Edge that has added the ability to block and configure the autoplaying videos with sound.
The latest Firefox Nightly comes with a feature to block sites the autoplay sound. You’ll find the option to “block sites that autoplay sound” under permissions section. At the moment, the default option is “Always Ask,” but you can change it to “Allow Autoplay” or “Block Autoplay”.
“We are adding the ability to block and configure autoplaying videos with sound in Firefox, can check it out in @FirefoxNightly today (comments welcome),” Mozilla engineer said in a a tweet.
— Dale Harvey (@daleharvey) July 21, 2018