HTML5 video should work in Firefox web browser. If it is still not working, try the following −
- Start Firefox in Safe Mode to check if any extension is creating issues.
To reach Extensions, go to, Firefox/Tools > Add-ons > Extensions - Try to turn off hardware acceleration.
- You need to check the media prefs that do not have the default value.
- If the media.windows-media-foundation.enabled is set to false, you need to set it to true and restart.
Any of the above fixes should work.