Video format or MIME type is not supported

Question

This is the relevant code to run video:

Answer 1

For Ubuntu 14.04

Just removed the package Oxideqt-dodecs then install flash or ubuntu restricted extras

and you are good to go!!

Answer 2

Firefox does not support the MPEG H.264 (mp4) format at this time, due to a philosophical disagreement with the closed-source nature of the format.

To play videos in all browsers without using plugins, you will need to host multiple copies of each video, in different formats. You will also need to use an alternate form of the video tag, as seen in the JSFiddle from @TimHayes above, reproduced below. Mozilla claims that only mp4 and WebM are necessary to ensure complete coverage of all major browsers, but you may wish to consult the Video Formats and Browser Support heading on W3C's HTML5 Video page to see which browser supports what formats.

Additionally, it's worth checking out the HTML5 Video page on Wikipedia for a basic comparison of the major file formats.

Below is the appropriate video tag (you will need to re-encode your video in WebM or OGG formats as well as your existing mp4):

<video id="video" controls='controls'>
  <source src="videos/clip.mp4" type="video/mp4"/>
  <source src="videos/clip.webm" type="video/webm"/>
  <source src="videos/clip.ogv" type="video/ogg"/>
  Your browser doesn't seem to support the video tag.
</video>

Updated Nov. 8, 2013

Network infrastructure giant Cisco has announced plans to open-source an implementation of the H.264 codec, removing the licensing fees that have so far proved a barrier to use by Mozilla. Without getting too deep into the politics of it (see following link for that) this will allow Firefox to support H.264 starting in "early 2014". However, as noted in that link, this still comes with a caveat. The H.264 codec is merely for video, and in the MPEG-4 container it is most commonly paired with the closed-source AAC audio codec. Because of this, playback of H.264 video will work, but audio will depend on whether the end-user has the AAC codec already present on their machine.

The long and short of this is that progress is being made, but you still can't avoid using multiple encodings without using a plugin.

Answer 3

In my case, this error:

Video format or MIME type is not supported.

Was due to the CSP in my .htaccess that did not allow the content to be loaded. You can check this by opening the browser's console and refreshing the page.

Once I added the domain that was hosting the video in the media-src part of that CSP, the console was clean and the video was loaded properly. Example:

Content-Security-Policy: default-src 'none'; media-src https://myvideohost.domain; script-src 'self'; style-src 'unsafe-inline' 'self'

Answer 4

FIXED IT!

I was losing my mind over this one. Reset firefox, tried safe mode, removed plugins, debugged using developers tools. All were to no avail and didn't get me any further with getting my online videos back to normal viewing condition. This however did the trick perfectly.

Within Firefox or whatever flavor of Firefox you have(CyberFox being my favorite choice here), simply browse to https://get.adobe.com/flashplayer/

VERIFY FIRST that the website detected you're using FireFox and has set your download for the flash player to be for Firefox.

Don't just click download. PLEASE PLEASE PLEASE SAVE YOURSELF the migraine and ALWAYS make sure that the middle section labeled "Optional offer:" is absolutely NOT CHECKED, it will be checked by default so always UNCHECK it before proceeding to download.

After it's finished downloading, close out of Firefox. Run the downloaded setup file As Administrator. It takes only a few seconds or so to complete, so after it's done, open up Firefox again and try viewing anything that was previously throwing this error. Should be back to normal now.

Enjoy!