Post a similar screenshot. see screenshot Did you try with Firefox in Troubleshoot Mode? https://support.mozilla.org/en-US/kb/diagnose-firefox-issues-using-troubleshoot-mode#w_how-to-start-firefox-in-4troubleshoot-modesf5safe-modesf

I tried troubleshooting mode and the problem is still there.

What OS? Your screenshot should be of the cnn page or another page where the video is not working. You can also try Refreshing Firefox. https://support.mozilla.org/en-US/kb/refresh-firefox-reset-add-ons-and-settings

Windows 10, video does work as stated above just no audio in the video on cnn. did you still need a screenshot?

Did you look at the mixer? see screenshot