They still can, no one is stopping them! All they have to do is compile ffmpeg in software only mode. It would be dog slow, but it's what you are after.

They are optimizing for the British education market, not for some ideal libertarian education market in Somalia that can ignore patents.

And licensing agreements are a bitch. It might be against Broadcom's license with MPEG-LA to give enough info about implementing MPEG-2 regardless of jurisdiction.