[hirundo]

> What does a blockchain actually solve here?

Immutability. Once a link gets on the blockchain you can depend on it not changing. The content it points to can go away, but with an immutable index, that is discoverable. Censorship and link rot are more evident.

[lokedhs]

So if someone uploads a 2 hour version of a rickroll and tags it with the name of the latest blockbuster movie and then takes it offline, there is now going to be a permanent record that at some time there was a copy of this movie uploaded? When in fact that never happened?

How is this in any way better, or even something beneficial?

[hirundo]

Tamper evidence. The blockchain link would include a hash of the contents, making it impractical to modify rather than disappear content.

[lokedhs]

Sure. It will contain the hash of the rickroll video. That doesn't help with the question as to who proves that the content is what it claims to be?