It's probably safe to assume that most people susceptible to fake news are computer-illiterate. Or at least, not as technical as the HN crowd. Why would normal people suddenly start listening to some nerd mumbo-jumbo they don't understand?
In the same way that signing keys are used by infrastructure & many who don't understand the nuances.
I guess you could always have the unedited version posted and verified, but that has its own difficulties too.
For press briefing, chaining to something like a White House press root is feasible.
But what about "married congressperson caught in local hotel with fling"? Or in one-party consent states, secret recordings? Self-sign? Sign with news organization (those that still exist) after sharing additional documentation?
[1] http://archive.is/paG5C [2] https://twitter.com/rafsanchez/status/896654656348323841
This is nothing more than legacy media bemoaning that media production (and propaganda production) has now moved mainstream and is out of their control.
In the end its a good thing, having a "trusted news sources" is not a normative expectation to any critical thinking based society. Everything should be viewed critically and viewed somewhat suspiciously. The entire concept of "trusted news" only has real appeal to the intellectually lazy. There is no objective truth in matters of politics, economics, society. Having some class of companies designated as "Trusted" has 1000x scarier potential than "view everything as a potential political statement".
So the insidious thing? Creating 100 videos with only slight political position adjustments, and thereby (even if the videos are later revealed as fakes!) shifting a voter's "gut" impression of a candidate.
I'd be amazed if we don't start seeing audio & video cryptographic authentication in the next 10 years. The subject of an interview gives me a box containing their private key, and video is looped through it and signed as we record.