Disable HTML5 Fullscreen Video Warning in Firefox

These days I have almost stopped watching anything on the television – I rarely use it and when I do, it is because some friends want to play FIFA on the play station. I watch all the shows and news on online media streaming sites like Hulu, Twitch and Netflix. All of these sites are now making use of the latest HTML5 video technology. But when you switch any video or streaming media being playing using the HTML5 video tag, it shows a warning that you have switched to full-screen mode. You have to choose “Allow” or “Deny” from this warning each and every time you switch to the full-screen mode. This can be annoying an inconvenient for people who watch videos in the full-screen mode regularly.

Firefox Disable HTML5 Video Alert

Fortunately, there is a simple add-on called Disable HTML5 Fullscreen Alert that can completely and fully make this warning disappear from Mozilla Firefox. This add-on is very basic and has no options or settings for configuring. As soon as you install this add-on, it goes to work right away and you will no longer see the full-screen alerts on HTML5 videos.

Firefox Disable HTML5 Video Alert

You can also change one preference in Firefox to disable the HTML5 full-screen alert. Here is how:

  1. Type about:config in the address bar in Firefox and press Enter.
  2. Search for a preference named full-screen-api.approval-required in the search box.
  3. Double-click on this preference and toggle its value from true to false.Firefox Disable HTML5 Video Alert
  4. That’s it. Now you will no longer see the full-screen alert on HTML5 videos.

Conclusion: There are more than one ways to disable the full-screen alert for HTML5 content. You can use either the Firefox extension mentioned above or just make changes to the preferences in Firefox yourself. In both cases, you can enable the full-screen alert once again by resetting the full-screen-api.approval-required preference value.


  1. This is NOT WORKING anymore with Firefox 43. I already have this set to false from the LAST TIME Firefox initiated this sort of popup. The NEW full screen popup needs to be dealt with. Mozilla, knock it off!!

  2. The second solution no longer works on Firefox 43. This preference is set to false on my computer and I still get the nag popup.

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