[orblivion]

These organizations are already incentivized, somehow or other, to do the work of creating and maintaining their archives. I think their incentives are aligned with wanting them to be authenticated. If you think gas fees would be a concern, they could create and publish a manifest file once a year for any new videos, and write the hash of the manifest file to the blockchain. That's one hash published a year, that can't be a lot.

[orblivion]

Though I guess if you're worried about whether something happened last week, you'll want more speedy publishing of hashes. But for any events that happen _in_ that future, we probably won't have much reason to trust videos anyway. That's a whole other problem. Fake news vs fake history.