Trust in a Trustless Society

So I've been having these thoughts about trust in a trustless technological society.

We are at the point now where anyone can make a video of anyone saying anything, provided there is enough information out on the web to sample from. And this technology is in its infancy. This is so far beyond photoshopping images that it is mind boggling. The technology is not mass-marketed yet, but give it 5 years and the guys using After Effects to make funny .gif memes will be making videos of political figures saying things that could lead to war... if they actually happened.

To my mind there are huge ramifications for the news and other factual publishing industries. How do you know that the video you are watching of someone saying something is real? How can you know?

In a weird way, this kind of technology will make us rely on trust more than ever. How can I know that this video of the President saying the Prime Minister is Prime Poopy Pants is real or fake? Well, it comes from this guy, so I'm pretty sure it's fake. Or maybe it comes from this other guy, whom I trust, so I'm pretty sure it's real.

Mis-quotes, spin, and faulty source material are already a huge problem for journalists and the levels of trust the public shows in the media reflect that. How much worse is it going to get?