HTML5 video not playing in Firefox

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.