> Ordinary people with the right tools built into their devices will be able to see very easily "Is it in the chain?" based on a simple enquiry to the ledger, and if the answer is no, then it's untrustworthy.

Not that I disagree, but the first thing that came to mind when I read this part of your comment was that this approach reinforces the Monopoly of governments and media companies on the flow of information. On the one hand it's great that we could protect in this way from unverified, "not-in-the-chain" messages, but on the other hand being a contrarian, producing and coming into contact with information outside of the chain, not necessarily really fake videos, but other types of information is crucial to social evolution and civil discourse.

The "public" and "distributed" would be major priorities of mine in the scenario you describe.