Earlier quoted context omitted.
There's a relatively simple solution to this that another heavy hitter in the FOSS world has been using for years: Prompt for a "restricted package" install when the user first encounters an h.264 video, similar to how Ubuntu deals with non-FOSS drivers, plugins, and codecs. It's the best of both worlds; you stay free and you get to be compatible.
Mozilla links directly with liboggplay and actively avoids abstracting it in any way. It can't handle any non-ogm container formats, and ogm was intentionally designed not to handle any other codecs. They're just assholes. If software patents are repealed in the US they'll mourn the loss of the mainstay excuse with which they force earnest activist wankery on their users. If patents were the real obstacle they'd dist…
There are plenty of other containers, audio formats, and video formats that are believed to be mostly patent-free; the same status as Theora. Firefox won't support any of them. Not Dirac the video format, not Matroska the container format, not FLAC the audio format, and so forth. Despite the fact that, for example, Matroska is far better-designed, more capable, and more popular than Ogg.
Mozilla could care less about patents: all they want is to promote their pet solutions at the expense of everyone else.