[IshKebab]

It lets you prove a file was not modified after a certain point in time. So if you have two similar videos that are both timestamped you can prove which one is the original.

This idea dates back to way before bitcoin.

https://en.m.wikipedia.org/wiki/Trusted_timestamping

[eivarv]

You only prove which was timestamped first, though - not which is the original.