Saying "Firefox will support H264 and MP3 decoding with OS codecs" is just speculation.
Quoting directly from the link:
Initially this will be enabled on Gonk (B2G). In a few weeks we will add support for Android as well. We will support encoding any video/audio format that is supported by existing decoders present on the system, including H.264 and MP3.
Of course it's possible that the bug doesn't land. But calling this speculation? Please.
It would be an interesting position for Mozilla to take, to capitulate on this issue on Mozilla's very own platform (B2G) and the fastest growing mobile platform Mozilla is currently active on (Android), yet not do so on the platform where the largest current userbase lies.