Who or what determines what's in your Facebook Newsfeed? It's a complex algorithm that aims to put what interests you most at the top of the queue. Increasingly, Facebook is focused on trying to determine what content is fake, junk or misleading - and sending it to the bottom. But the purveyors of this content are a determined adversary. Miles speaks with their foe at Facebook, the Director of Analytics for the News Feed, Dan Zigmond. It's an interview we did for our upcoming series on "junk news" for the PBS NewsHour.