Imagine that signature is embedded in a way that survives video re-coding.
It appears that most of this can be solved by suitable cryptographic algorithms built into digital…
Aleksandr Bulkin

Hard to imagine.

What about privacy? (anonymity) if you embed any key, anyone can gain knowledge who is owner of the key.

I like the idea and might be used to “record” political debates or whatever that needs to be verifiable – essentially every recorded media needs to be verifiable.