I think we need a chain of custody system for content, but that would require browsers, software, websites, operating systems, phones, camera manufacturers, etc to all get on board. But each intermediary or source (optionally) cryptographicaly signs a piece of content that it either generates, edits, or passes along, and the end result at a destination, is that content is either 'trusted' if its cryptographic chain is solid, or un-trusted otherwise.