Native H.264 playback is supported on Windows and Linux platforms but the only bug I can find for Mac support is here:
https://bugzilla.mozilla.org/show_bug.cgi?id=851290
However, even though that bug was completed successfully, the code never made it into the main repository and according to the comments on the bug, the plan for the Mac has changed.
I'm a little confused because I can find no mention anywhere of what this new plan is nor any bugs for Mac playback support. I would guess the new plan is probably OpenH264 but I cannot find any bugs mentioning playback support (only WebRTC is mentioned) so presumably no-one is working on this if there is no bug.
Can someone clarify what the plan is and point me in the direction of the relevant bugs?