Use YouTube without flash installed in Firefox

Being a Firefox user, you might face an issue that some videos do not play for you when you don't have Adobe Flash installed. Luckily for us, Firefox is an HTML5 compatible browser. Instead of installing Flash, you can tweak the browser and make YouTube work for you without Flash. To get it working, you need to enable the Media Source Extensions feature which is disabled by default.

To check the Media Source Extensions feature state, we can refer to YouTube's HTML5 test page.
Click this page in Firefox to open it.
From the picture below, you can see that the browser does not have Media Source Extensions yet.
no mse
Let's enable it.

  1. Open a new tab and enter the following text in the address bar:

    Confirm that you will be careful if a warning message appears for you.

  2. Find and set the following value to true:
  3. Right-click the values list and execute New > Boolean:
  4. Name it media.mediasource.ignore_codecs and set to true.

  5. Restart Firefox and visit the same HTML5 page:
  6. Click Request the HTML5 Player to switch YouTube to HTML5:

Now your Firefox browser will play more videos and not only at YouTube.
If this trick makes your Firefox less stable or produces some other issues, it is easy to set everything back:

  1. Set media.mediasource.enabled to false in about:config.
  2. Go to the YouTube HTML5 page and click "Use the default player".
  3. Restart Firefox.

That's it.

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Author: Sergey Tkachenko

Sergey Tkachenko is a software developer who started Winaero back in 2011. On this blog, Sergey is writing about everything connected to Microsoft, Windows and popular software. Follow him on Telegram, Twitter, and YouTube.

5 thoughts on “Use YouTube without flash installed in Firefox”

  1. I knew about YouTube HTML5 support long time ago but this, updated version of the trick, sounds even better. Can‘t wait to test this out!

    1. It looks like I didn‘t read the title when I wrote this comment. HTML5 in YouTube works without changing that option. At least in my case, changing it led to problems when playing videos.

      1. Hmm. I am using it (well, it is Linux Firefox without flash installed). In my personal case, with MSE enabled YT works better for me.

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