alt Hacker NewsYou're talking about the metadata of the files, which can always be edited and someone will inevitably try to make software to do exactly that. Also, Adobe's proposal for handling generated content is exactly this and they're not able to get buy-in from other companies.
Edit the metadata in what way? It's a cryptographic hash.
If the bits that make up the video as was recorded by the camera don't match the hash anymore, then you know it was modified. That doesn't mean it's fake, it just means use skepticism when viewing. On the other hand the ones that have not been modified and still match can be trusted.