Opening a fixed mini player automatically is a feature offered by the website and is created via JavaScript if the main player is scrolled out of view. A lot of websites now have a fixed (pop-up) mini player in one the corners once you start plying a video that stays visible if you scroll the page. This website mini player shouldn't be confused with the Firefox PiP (picture-in-picture) feature (you likely see the PiP icon if you hover the player). ---- You can look at these prefs on the the <b>about:config</b> page to see what settings work for you to block autoplay. *media.autoplay.default = 5 [0:allow;1:blockAudible;2:Prompt;5:blockAll] *media.autoplay.blocking_policy = 2 *media.autoplay.allow-extension-background-pages = false *media.autoplay.block-event.enabled = true You can open the <b>about:config</b> page via the location/address bar. You can accept the warning and click "I accept the risk!" to continue. *https://support.mozilla.org/en-US/kb/about-config-editor-firefox ---- *https://support.mozilla.org/en-US/kb/block-autoplay