Stop video autoplay in Firefox, including muted videos

Open the Firefox menu and choose Settings. Search Settings for autoplay, then open Settings beside Autoplay. Under Default for all websites, select Block Audio and Video and click Save Changes. This is the option for preventing muted clips from starting too.

Reopen the Autoplay settings list and look for the website. Its own permission can override the default. Change that entry’s status, or select it and use Remove Website to return to the default. Save Changes, revisit the page and check before clicking the player.

Open Page Info with Ctrl + I on Windows or Command + I on Mac. In Permissions, find Autoplay. Clear Use Default if you want a separate choice for this site, then select the blocking or allowing option you need. Page Info permissions apply to the site’s domain.

If you want to watch a clip, try its play button after checking the permission. An autoplay preference concerns automatic starts; if your problem is that a chosen video will not play at all, use Mozilla’s playback troubleshooting linked from the autoplay help page.