Mozilla will shut down Pocket’s services on July 8, 2025. At that time users will no longer be able to access the Pocket website, apps and API. You can export your saved items and API data until October 8, 2025 before they are permanently removed. For more information, see this article.

Avoid support scams. We will never ask you to call or text a phone number or share personal information. Please report suspicious activity using the “Report Abuse” option.

Learn More

Youtube Videos do NOT play if media.mediasource.enabled is set true (Youtube with HTML 5 Player). WHY?

  • 2 replies
  • 10 have this problem
  • 823 views
  • Last reply by Markus12

I am Using the new HTML 5 Player when watching Videos on Youtube. It works just fine when media.mediasource.enabled is set to "false" but then I cannot get the full experience because the lack of features!

If I enable it, NO Video is going to load, meaning I cannot watch any Video on Youtube! As a workaround I installed the Plugin "Youtube Control Center" (missing in your List below). But it would be nice if I would NOT have to use this...

Even better would be if Firefox would Support WebM. But this does not seem to be the case since YT uses exactly this Format with its new Player... (And if I enable this media.mediasource.enabled (set it "true") NOTHING works anymore.)

I am Using the new HTML 5 Player when watching Videos on Youtube. It works just fine when media.mediasource.enabled is set to "false" but then I cannot get the full experience because the lack of features! If I enable it, NO Video is going to load, meaning I cannot watch any Video on Youtube! As a workaround I installed the Plugin "Youtube Control Center" (missing in your List below). But it would be nice if I would NOT have to use this... Even better would be if Firefox would Support WebM. But this does not seem to be the case since YT uses exactly this Format with its new Player... (And if I enable this media.mediasource.enabled (set it "true") NOTHING works anymore.)

Chosen solution

Firefox plays the "old" WebM format in its default configuration (media.mediasource.enabled=false). You can verify that here: http://www.webmfiles.org/demo-files/.

From what I have read, turning on MediaSource will allow you to play the "new" WebM on YouTube starting in Firefox 31. Even though the preference exists in Firefox 30, I don't think the actual code is there, which would explain why advertising that capability to YouTube causes total failure.

See: http://www.ghacks.net/2014/05/10/enable-media-source-extensions-firefox/

Read this answer in context 👍 2

All Replies (2)

Chosen Solution

Firefox plays the "old" WebM format in its default configuration (media.mediasource.enabled=false). You can verify that here: http://www.webmfiles.org/demo-files/.

From what I have read, turning on MediaSource will allow you to play the "new" WebM on YouTube starting in Firefox 31. Even though the preference exists in Firefox 30, I don't think the actual code is there, which would explain why advertising that capability to YouTube causes total failure.

See: http://www.ghacks.net/2014/05/10/enable-media-source-extensions-firefox/

THANKS for the Answer! I just downloaded Aurora (Firefox Version 32) and it works just fine!