I don't buy the "we're a poor non-profit" bit that people keep attributing to Mozilla - did they ever say that? Their income in 2009 alone was over $100m, pretty much all from google. I can believe it's an ideological stance though.

On the android phones, H264 decode (and sometimes encode) is built into the hardware - this will have been paid for by the chip vendor and rolled into the chip price. I don't believe google "sublicense" H264 decode.

As for HW accelerated WebM decode - recent video decode engines tend to be more programmable than the older ones which were very very hard coded in silicon for maximum efficiency... but there could well be many roadblocks that prevent any current hardware from being able to effectively hardware-accelerate WebM decode (it doesn't take much to throw a spanner into the works of hardware that's been highly optimized for existing standards).