FirefoxNightly] H264/MP4 playback not supported · Issue #22 · xhorak/firefox-devedition-flatpak · GitHub
![Each attempt to view a video on a particular site I get this message," Video format or mime not supported". How do I fix this? | Firefox Support Forum | Mozilla Support Each attempt to view a video on a particular site I get this message," Video format or mime not supported". How do I fix this? | Firefox Support Forum | Mozilla Support](https://user-media-prod-cdn.itsre-sumo.mozilla.net/uploads/images/2017-01-21-20-42-34-a28e4a.png)
Each attempt to view a video on a particular site I get this message," Video format or mime not supported". How do I fix this? | Firefox Support Forum | Mozilla Support
![Trying to Enable MP4 on FF 52.4.0, do I need to reinstall? | Firefox Support Forum | Mozilla Support Trying to Enable MP4 on FF 52.4.0, do I need to reinstall? | Firefox Support Forum | Mozilla Support](https://user-media-prod-cdn.itsre-sumo.mozilla.net/uploads/images/2017-09-29-20-03-15-519ffe.png)