Started having a problem lately on Sigforum where most posted youtube videos only show as a black box or a black box and the message Playback isn't supported on this device.
I'm using an 27" Imac with Monterey OS and Firefox browser. This doesn't happen using Safari or Brave browsers.
Hoping someone can tell me whats going on with Firefox such as a setting that needs to be changed.
Thanks for any help.

Heres a you tube video on fixing firefox issues with video playback you can use Safari to see it..

Thanks HRK that video pointed me in the right direction. Problem turned out to be a browser extension that the creator of has apparently decided not to support Firefox anymore.