A blockchain could be a way to store and publish that signature & hash.
It can't say "this is real", it can only say "that signature belongs to source X".
yes but it would be a bad one. We have multiple key distribution mechanism that are better for the use case.
Adding Blockchain into the mix is superfluous, and destroys scalability.
The TV will have to match every short segment - perhaps 5 seconds of video - against a blockchain which scores the validity of that segment - and of course looking back to it's original source. Signing the whole video is necessary but not sufficient.
But yes, this is going to be resource-intensive.
Why not just allow a cert with that information to be delivered alongside the video? Where would the "score" come from?
Crowd-sourced is already "network of trust".
An AI based score would have to be produced by a centralized provider, so network of trust is the reality for that too.
The only way blockchains would provide benefit would be as a distributed discovery mechanism for "review" of the video chunk and having an open ecosystem for that (a dht or trackers) would work better.
Blockchains only ever had a reasonable use case under the assumptions of functional capitalism (and we don't have one of those). The reality is that they can't be sustainable without capture and the market incentives only increase the incentive to capture it.
DHTs and Networks of Trust only have the value of what service they provide and while that is less exciting for scamming people, they have survived and been high functioning for decades.
Simple answer is I can just record a deep fake and get it cryptographically signed.