Widevine use in a fresh profile will trigger a content doorhanger informing the user a browser component is installing. For OpenH264, there's no UI displayed. Maybe we can repurpose what we use for Widevine here.

Just to add some detail:
I think it would be best if there were a UI somewhere that allows for manual triggering of the download+install of openh264 that gives feedback about what's happening -- i.e., whether it's in progress, and whether it succeeded/failed with specific error messages if applicable.

Currently, if OpenH264 fails to download/install, the FF installation is left in a state where it cannot negotiate H264 calls, and there isn't a formal process for the user to know what's wrong or to remedy the situation, and those of us with WebRTC applications don't have a good place to point Firefox users to when they run into this.

A UI like this would go a long way toward helping the situation.