That's why the word "blanket" is included there - if you just give Firefox and Firefox alone a royalty-free H.264 license, that's not compatible with Free Softw

That's why the word "blanket" is included there - if you just give Firefox and Firefox alone a royalty-free H.264 license, that's not compatible with Free Software, you can't legally fork it without getting another patent license that will almost certainly cost money. AFAIK the thing Firefox refused to accept wound up happening anyway. Cisco released a nominally BSD-licensed H.264 decoder and agreed to pay the maximum royalty possible to MPEG-LA. If you use their specific codec binaries, then you're covered under the patent license. So Mozilla wound up writing a new plugin framework specifically to host OpenH264 so that WebRTC could have a standard codec.