Issues relating to this were reported on some crappy forum (see below). Luckily this is another case of near-free work from some other platform codebase no one cares about.
The addition of this Google format codec string is desired so we can accept these kinds of strings as codec data and have better web compatibility.
PM Forum Topic 27934
BMO Bug 1407919
MozPatch Credit James Cheng <email@example.com>
James Cheng <firstname.lastname@example.org>