It's a brilliant hack, they pay exactly zero for this.

You get a licence from Cisco, and they pay royalties to the MPEG LA for that licence. Now, the H.264 licence fees are per copy distributed, but there's a cap on the fees, and Cisco's own usage puts them _way_ over the cap anyhow, so distributing this thing freely for Mozilla to use costs them literally nothing at all. Plus, they're apparently really distributing binaries for any and all platforms you can think of (someone mentioned S/360).

The Cisco binary should include encoding as well as decoding for it to be usable in WebRTC. Production systems could download Cisco's binary and use it.