https://support.mozilla.org/en-US/questions/1359657#answer-1463359 and updated to 95.0. . . . I finally found where the plugin "Widevine Content Decryption Module provided by Google Inc." was not updating to the newest version of December 1, 2021. Ver #4.10.2391.0

cor-el; Make sure you have the latest Widevine version. You can toggle DRM off/on to see if that makes Firefox (re)load DRM components.

• Settings -> General: Play DRM
• https://support.mozilla.org/en-US/kb/enable-drm

You can possibly check the XHR requests in the Browser Console if this doesn't work.

• https://developer.mozilla.org/en-US/docs/Tools/Browser_Console

https://support.mozilla.org/en-US/kb/fix-problems-images-not-show

http://kb.mozillazine.org/Images_or_animations_do_not_load

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

Hi there, You can try clearing Firefox’s cache, which may help with the video playback issues. To do this, access the Firefox Options from the menu. Select on the Privacy & Security tab, and under History select Clear History.

Update graphics driver Or you can try to update your graphics driver. Maybe the graphics driver clashing with Firefox Quantum and an update might be in order.

Remove conflicting add-on Conflicting add-ons can cause Facebook video playback issues on Firefox Quantum. In this case, it’s necessary to isolate and delete the troublesome add-on.

Adjust Performance Setting Go to the Performance section under the General tab. Then deselect the ‘Use recommended performance settings' option.

I hope this will help you.