how does putting the vide on chain, etc... gives the ability to verify if it's real or not? heard a lot of people talking about this, what's the best thing to read on the topic?

how does putting the vide on chain, etc... gives the ability to verify if it's real or not? heard a lot of people talking about this, what's the best thing to read on the topic?
https://twitter.com/shaunmmaguire/status/1758197940253000056

Less abt being onchain although that adds properties. Onchain gives us ownership & proof of existence at or before a time. Time is important more than ownership here. ‘real’ is not a property.  It’s knowing a person was in possession of the content (signed by) so they can eg ‘…I approve this message/video’