I'm running Firefox (12.0 beta), and whenever a video is available in HTML5, it will open in that. I have opted-out of the HTML5 preview (I saw a post suggesting to opt-in then opt-out again, which I did... this had no effect). I want to force it to use the Flash Player always.

EDIT: I'm using Windows 7.


  • Is Firefix without webm support is out of the question?
    – Eroen
    Commented Mar 28, 2012 at 7:03
  • Are you sure Flash is installed and enabled properly? Check about:plugins and a Flash test page e.g. Adobe's test page or a Flash based game.
    – Bob
    Commented Mar 28, 2012 at 7:45
  • 1
    @Eroen - No, if I can somehow remove the WebM support from Firefox that would be fine. Commented Mar 28, 2012 at 9:19
  • 1
    @Bob - Yes; it uses Flash on videos that don't have WebM versions (most of them). I want to use it on all videos it can be used on. Commented Mar 28, 2012 at 9:19
  • @Fraser I meant to put the word "compiling" in there somewhere. I'm hesitant to put it as an answer, as I really hope there is a configuration solution.
    – Eroen
    Commented Mar 28, 2012 at 9:52

3 Answers 3


In the comments for this enhancement request there is a suggestion (comment 5 at 2012-03-13 15:57:41) to set media.webm.enabled, media.ogg.enabled and media.wave.enabled to false in order to "render <video> and '' elements unable to play anything."

All these options are readily available if you enter about:config in the address box, and then enter media. in the filter box. In my testing (Firefox 10.0.1 on Gentoo) it was not necessary to restart Firefox, the elements were disabled when I reloaded the page.

This page was useful for my tests. The video there is disabled when both media.webm.enabled and media.ogg.enabled are set to false, as there is fallback from one to the other.

There were rumors reently that future Firefox will support h.264, in that case you might have to disable that too after an update.


Download an add-on called YouTube Flash Player. It will automatically force YouTube to use the Flash player, not HTML5.

  • 1
    Please read How do I recommend software for some tips as to how you should go about recommending software. At the very least you should provide more than just a link, for example some additional information about the software itself.
    – DavidPostill
    Commented Feb 18, 2015 at 15:14

goto -> about:config -> media.windows-media-foundation.enabled -> false

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