We hope a standard will be created and used by all digital content creation tools. But this will take time. And even then, bad actors will not be deterred. They will find ways to create fake content and pass it as authentic. We want to be there to fight them every step of the way!

How do you hash something so fuzzy as video / speech? Two different microphones picking up the same audio will result in two digital recordings that hash differently.

That's the problem. It would require some kind of new fuzzy signature algorithm, which works on information content in speech, rather than raw audio data. In this case, exact matching of data isn't important, but major changes in information, so that changing / removing / adding words wouldn't be possible. Simple way would be to just convert speech to text first with a known method, so that both microphones could work from the same source data. The display device could actually show real-time transcription of the speech along with the signatures.