FIX: Firefox MIME video not supported error

by Matthew Adams
Matthew Adams
Matthew Adams
Windows & Software Expert
Matthew is a freelancer who has produced a variety of articles on various topics related to technology. His main focus is the Windows OS and all the things... read more
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  • The Firefox MIME video not supported error is likely to pop when trying to play content from websites that run on outdated plugins.
  • Since browsers, including Firefox, have gradually turned their back on plug-ins to embrace HTML, MIME video format errors are more and more common.
  • So what do you do when you get the Firefox MIME type not supported notification instead of your video?
  • That's easy! If Firefox says that video format or MIME type is not supported, try cleaning it a bit or go for a different browser.
firefox mime video not supported
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Are you getting a Firefox MIME video not supported error when attempting to play videos in your browser? When that happens, the videos display this error message: Video format or MIME type is not supported. Thus, the video doesn’t play in the browser. One Firefox user stated:

When attempting to watch any program on there is an error message across the screen where I would normally see the program. ‘Video format or MIME type is not supported,’ I have never had this before with Windows XP or Windows 10.

Mozilla, and other browser developers, have ditched plug-ins in favor of HTML5. As such, Firefox no longer supports most plug-ins. However, there are still quite a few websites that include media content that depends on antiquated plug-ins.

Consequently, videos on sites that haven’t been updated are returning Firefox MIME type not supported errors. Here are a few potential fixes for the MIME video format problem.

How do I fix no video with supported format and mime?

1. Switch to a different browser

If the MIME video format errors persist in Firefox, consider making the switch to Opera. You must know that you will not be missing out on any features that you already like. Video pop-out is available in Opera as well. It was actually first introduced here and then other browsers copied it.

Support for extensions is also present and so are the Dark Mode or Built-in Snapshot options. Besides, you’ll get to enjoy extra perks such as a free, unlimited VPN, built-in messengers, unit converters, and a lot more.


Make the switch and enjoy the perks with editable MIME types for improved support.

2. Clear Firefox’s cache

  1. First, click the Open menu button at the top right of Firefox.
  2. Select Options to open the Options tab.
  3. Click Advanced > Network to open the settings shown directly below.
  4. Press Clear Now to the clear the cache.

A corrupted cache can generate website errors. So clearing Firefox’s cache could feasibly fix the Firefox MIME video not supported failure.

If you need more info on how to clear Firefox’s cache, check out this handy article right away.

3. Clear Firefox’s cookies

  1. Deleting corrupted cookies might also resolve the Firefox MIME type not supported error. To do that, open the Options tab in Firefox again.
  2. Select Privacy and select Use custom settings for history from the drop-down menu.
  3. Then you can press Show Cookies to open the window directly below.
  4. Press the Remove All button to erase the cookies.

Performing these operations is safe, but a bit time-consuming. Fortunately, there are best practices to keep your computer in shape and remove old files, junk, cookies, and cache.

The most secure and time-efficient solution to erase cookies from your browser is using cookie cleaning software, that removes them efficiently.

This type of tool will scan your browser and give you an easy-to-follow report on all the clutter that can be deleted. Just select what you want to remove and let it complete.

4. Install the Media Feature Pack on KN and N Windows editions

Not all Windows editions include the media-related technologies Firefox needs to play media content. Windows KN and N editions don’t include Windows Media Player, WMP Active X, the Windows Media Device Manager, Windows Media Format and are also missing a few audio codecs.

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As such, missing media technologies can also be a factor behind video and audio playback errors in Firefox for Windows KN and N users. Installing the Media Feature Pack will restore many of the missing media features in KN and N editions.

There are different Media Feature Packs for different versions of Windows 10 KN and N. You can download the packs from any of the three pages below. Install the Media Feature Pack that best matches your Windows 10 version.

5. Add the NoPlugin extension to Firefox

If the MIME type error still isn’t fixed, check out the NoPlugin add-on for Firefox. This add-on scans website media content for plug-ins and converts the plug-in code to HTML5 so that you can play the video in your browser.

If the browser still can’t play the media content, NoPlugin downloads the video so that you can play it on a media player. You can add NoPlugin to Firefox by pressing the + Add to Firefox button on this website page.

With the add-on installed, open the web page that includes the video displaying the Firefox MIME video not supported error message. Now the video might work in Firefox.

If the video still doesn’t play, press the Open content button to download the media content. Then you can play the video on a media player that supports the video format.

If the videos still aren’t playing in Firefox with the NoPlugin add-on, you may need to update the browser to a version that fully supports HTML5.

You can update Firefox by clicking the Open menu button > Open Help Menu > About Firefox. That will open the window below from which you can press a Restart Firefox to Update button.

Those are a few fixes for the video format or MIME type is not supported error that will restore video playback in Firefox. As the web continues to embrace HTML5, more and more sites will become HTML5 compatible.

That will reduce plug-in video errors, but for now, the NoPlugin add-on is a good remedy for websites that still rely on outmoded plug-ins.

That’s about it! We hope our solutions helped you get rid of the Firefox MIME type not supported error. If you have any other questions, don’t hesitate to leave them in the comments section below.

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