videos play fine in firefox 35.0 but not in any upgrade version since(including 42.0) troubleshooting between the 35.0 and 42.0 , i noticed the media.windows-media-foundation.enabled option is not in the about:config list when i upgrade from 35.0 to anything newer if i roll back to 35.0 , media.windows options are in the about:config again no luck when i toggle the plugins.addons,enable as suggested in support solutions