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.