To be certain, lots of conjecture on my part. I just found it very interesting that Microsoft is essentially taking on the h264 licensing fees for Firefox by releasing a h264 plugin for the browser. (I'm assuming that MS will be footing the licensing fees -- or maybe they're just covered by a blanket $6.5 million fee, so it's just the cost of building the plugin that they really have to eat)
My extrapolation is a reach, but supporting h264 on Firefox doesn't make sense except if MS is seeing cash from h264 ubiquity.
Microsoft's Firefox add-on simply replaces the browser's <video> player with a Windows Media Player object, so the fees have already been paid for as part of their licence to include an H.264 decoder with all copies of Windows.
Supporting H.264 makes sense for Microsoft as a licensor of the patent pool.
My extrapolation is a reach, but supporting h264 on Firefox doesn't make sense except if MS is seeing cash from h264 ubiquity.