Things I already tried: Reinstalling Firefox Reinstalling Flash

Is this with many websites, some, a few?

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

https://support.mozilla.org/en-US/kb/fix-common-audio-and-video-issues

https://support.mozilla.org/en-US/kb/html5-audio-and-video-firefox

https://support.mozilla.org/en-US/kb/troubleshoot-issues-with-plugins-fix-problems

https://support.mozilla.org/en-US/kb/warning-unresponsive-plugin

Pretty much every Website other than Twtich and Youtube. For example I can't watch Amazon Prime Video as well since I updated from Windows 7 to Windows 10. I get a weird message about the DRM Plugin not working.

Again: The only thing changed is that I updated from Windows 7 to Windows 10. Everything works as before on Google chrome but Firefox is on a wild rampage since the update. I tried the https://www.microsoft.com/en-us/software-download/mediafeaturepack but it can't be installed on my system.

So I deleted every single file and registry entry regarding Firefox and did another completely fresh install. I still have the same problems i.e. Amazon Prime Video not working (WCD Module is set to always active but doesn't work) and the "No compatible source was found for this media." message on every site other than twitch and youtube.

I hope someone has a clue about what is going on with Firefox and my system :).

P.S.: Everything works in google chrome so it shouldn't be system related.

When you updated Windows to 10, did you also update all 3rd party programs?

First, can you confirm that Firefox is able to use the Media Foundation files for H.264 / MP4 video? Some test pages:

• https://www.youtube.com/html5 (look for blue next to H.264 items)
• https://www.quirksmode.org/html5/tests/video.html (ignore the red and green boxes and scroll down to the first player under "H.264/MP4")

Second, once that is confirmed to work, for DRM video (Amazon/Netflix), you will need Google's Widevine plugin. See:

Watch DRM content on Firefox

jscher2000 said

First, can you confirm that Firefox is able to use the Media Foundation files for H.264 / MP4 video? Some test pages:

• https://www.youtube.com/html5 (look for blue next to H.264 items)
• https://www.quirksmode.org/html5/tests/video.html (ignore the red and green boxes and scroll down to the first player under "H.264/MP4")

Second, once that is confirmed to work, for DRM video (Amazon/Netflix), you will need Google's Widevine plugin. See: Watch DRM content on Firefox

On the Youtube-page H.264 and MSE & H.264 have a red Exclamation mark next to them. Same on quirksmode, H.264/MP4 is being grey.

Widevine plugin is installed and marked as "always active"

Did you check this?

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

cor-el said

Did you check this?

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

Yes I tried downloading the 1803 version and started it. It tells me that my system doesn't have the correct version. But my version is (according to winver): Version 1803 (Build 17134.81)

So, I guess this is one of these "format c" issues?

Zwirni said

On the Youtube-page H.264 and MSE & H.264 have a red Exclamation mark next to them.

Could you check the settings:

(1) In a new tab, type or paste about:config in the address bar and press Enter/Return. Click the button promising to be careful or accepting the risk.

(2) In the search box above the list, type or paste wmf and pause while the list is filtered

Are there any modified preferences in this set? You could try resetting them using right-click > Reset.

(3) In the search box above the list, type or paste mp4 and pause while the list is filtered

Are there any modified preferences in this set? You could try resetting them using right-click > Reset.

under wmf the following entry was "changed": media.decoder-doctor.MediaWidevineNoWMF.formats

under mp4 nothing was "changed"

I did what you said and reset the entry but nothing has unfortunately changed regarding my problems. Although I do believe it has something to do with the mediasource package. I guess I have to reinstall Windows 10 and see whether I can install it then.

Zwirni said

I tried the https://www.microsoft.com/en-us/software-download/mediafeaturepack but it can't be installed on my system.

This could be the basic issue, as you should probably download a Media Feature pack after the OS upgrade according to the Fix video and audio problems on Firefox for Windows N editions support article.

Be sure to check your Windows edition and try downloading the version that matches your build. Does it match any of the versions listed on this page ?

Tonnes said

Zwirni said

I tried the https://www.microsoft.com/en-us/software-download/mediafeaturepack but it can't be installed on my system.

This could be the basic issue, as you should probably download a Media Feature pack after the OS upgrade according to the Fix video and audio problems on Firefox for Windows N editions support article.

Be sure to check your Windows edition and try downloading the version that matches your build. Does it match any of the versions listed on this page ?

I was able to install: KB3099229_x64 All the others (including 1803) didn't work. Unfortunately it didn't change anything. And my build is, according to winver, Version 1803 (Build 17134.81)

I guess it is time to accept, that i need to format C because Upgrading from Win7 to Win10 horribly crashed the registry or something like that.

Are the results on both test pages exactly similar as before?

You may be able to fix this by installing K-Lite Codec Pack Standard as referred to in this article. I do think there should be an official answer and way to fix it though, but haven’t found that (yet).

Tonnes said

Are the results on both test pages exactly similar as before? You may be able to fix this by installing K-Lite Codec Pack Standard as referred to in this article. I do think there should be an official answer and way to fix it though, but haven’t found that (yet).

I installed this pack but unfortunately it didn't change anything :/.

Thank you all for your effort but I guess it is time to format C and reinstall.