When I view a story on CNN it plays in Flash. Your plugin list (next to your post, Question Details > More System Details) does not show that you have Flash installed, or maybe it has become disabled due to a security vulnerability.

Could you check the Add-ons page using either:

• Ctrl+Shift+a
• "3-bar" menu button (or Tools menu) > Add-ons

In the left column, click Plugins. Look for "Shockwave Flash" on the right side; it may be at the bottom where disabled plugins are listed.

If it is not there or cannot be set to either "Always Activate" or "Ask to Activate", you can get an installer from the following page:

https://www.adobe.com/products/flashplayer/distribution3.html

There is a specific row for the Firefox version of the plugin, and either the EXE or MSI installer will work.

Any improvement?

Hi, Thanks for the info. I just tried youtube live streaming and that worked. I don't see it in my plug-ins though. So I guess I can't set it to always activate. Does it matter? Is CNN different? I don't think there is any live streaming on CNN right now to test it.

Also, this is a new computer. I don't have any add-ons. Should I? do you have recommendations?

"Video format or MIME type not supported" is about the HTML5 media player, so the Shockwave Flash plugin shouldn't matter.

Does the HTML5 media player work otherwise?

YouTube would use the HTML5 media player as well in current Firefox releases, so if it works there then I would expect that it will work on other websites that use the HTML5 media player as well.

You could check the code used to play these media files in the Inspector to see what media types are offered.

• https://developer.mozilla.org/Tools/Page_Inspector

See also:

• https://support.mozilla.org/kb/fix-video-audio-problems-firefox-windows

If I disable Flash completely, then CNN sends an MP4 to be played in the built-in HTML5 video player. (It didn't occur to me to test that before because I wasn't sure that you had not yet installed the Flash plugin.)

Could you visit these two test pages and tell me the results:

(1) The YouTube HTML5 test page: do you have all blue boxes except the last one? If you have other red boxes, which ones are they?

https://www.youtube.com/html5

(2) H.264/MP4, WebM and OGG testers (scroll down past the text to where the players are supposed to appear):

http://www.quirksmode.org/html5/tests/video.html

Do any of those work?

On the Youtube page everything was as you described. On the other one lots of red boxes. Here is the screen shot.

Thanks, on that second page, please ignores the boxes and scroll down to where the players are and try the MP4/H.264 player.

Big Buck Bunny plays just fine! Am I cured?

What you posted above is a fixed (misleading) image that doesn't represent your setup, but merely shows the state when this page originally got created years ago (you will notice Firefox 4.0b11). You need to scroll down the page to see if Firefox plays all offered media types.

I have no idea what you mean. If the video on that page plays, isn't that an indication that my problem is solved?

thr33seas said

Big Buck Bunny plays just fine! Am I cured?

Well, it leads to a puzzle: if your Firefox plays H.264 video fine on YouTube and the test page, why is it having a problem on CNN? Is there a particular example on CNN you could link to that isn't working? Maybe it has some unusual difference I didn't see testing just one video (Japanese earthquake story).

Thanks for your help. I'm headed out for a while so I'll have to try later. Just don't want you to "stand by".

PS - the Youtube video and Buck played after I installed Flash not before. Meaning I had tried CNN before the install and Youtube after. I have to guess that CNN will now be ok too. No?

If you haven't tried CNN after installing Flash, that may work around whatever the issue is with the built-in HTML5 video player. But YouTube and the bunny test page do use the built-in player, so I think they don't really tell us one way or the other.