Change autoplay in permissions setting to block audio and video. These are not "popups", firefox pop out video player.

That works. Thank you.

This does not work for me. Videos follow me down the page in the sidebar. Often blocking some of the text. Are there about:config settings I can use? Addons? Anything?

You can look at these prefs on the the about:config 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 about:config 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

Thanks cor-el. It works better, especially in stopping autoplay on pages.

But popup videos still follow me down the sidebar on some pages. For example; on space.com pages such as this one: https://www.space.com/antarctic-ice-shelf-collapse-as-earth-warms

Also, can I add exceptions to the autoplay settings in Firefox options: Tools menu > options > Privacy and security > Permissions > Autoplay > Block audio and video. I would like to add an exception for Youtube playlists. To allow autoplay on them.

There is a box there. I am not sure what the box there does. I can't enter anything into it.

I am confused about popup videos mentioned lately every time Firefox updates. That apparently is a feature. But I saw no mention or link about how to turn them on or off.