The following webpage work around the autoplay by having a popover one has to click to close. https://www.thrillist.com/entertainment/nation/saturday-night-live-snl-thanksgiving-skits It is kind of a double jeopardy: Popover + autoplay video. Without popover, Firefox can disallow the video from autoplaying. But with the popover that gets dismissed when click on the close button (top right), it starts autoplaying. To reproduce: - on a clean profile or one you know you never visited the website, go to https://www.thrillist.com/entertainment/nation/saturday-night-live-snl-thanksgiving-skits - Tell Firefox to not autoplay - The popover should have appeared to annoy you - Click on the top right close box to dismiss the popover The video will auto play. (it shouldn't). - Close the tab. - Reopen the tab (ctrl-shift-T) - The popover will never appear, and the video will not autoplay. That's the behaviour I expect. To reproduce the autoplay, accessing the page in a private browser window is sufficient. Preferences are: media.autoplay.allow-muted;false media.autoplay.block-event.enabled;true media.autoplay.block-webaudio;true media.autoplay.enabled;false This is nightly 65.0a1 (2018-11-20) (64-bit) on macOS.

The video in question is the "recommended video" that gets moved on the page to make sure you don't miss it.

Alastor, can you please help me triage this issue?

Sorry, now we no way to prevent site using this kinds of way to workaround the blocking-autoplay mechanism now. We're planing to change our blocking autoplay from user-activation (Chrome style, that is to allow autoplay after document has been activated by user gesture) to user-click-handler (Safari stye, that is only allow autoplay which is triggered inside user event handler), but this work is depending on DOM team's implementation which is still in the process.