Great doc, watched it awe at some of the footage and the discovery that stoney meteors can cause more damage than predicted. Your views on government conspiracy to prevent public knowledge of large, Earth bound asteroids needs further thought. If...
(a) government already knows of an extinction level event impact due to strike soon and they have nothing to defend against it, what would be the sense of telling the world we're going to die days, weeks, months or years before we will because we know anarchy will rule, people will feel free to do as they please with no long term consequences.
(b) government doesn't expect ELE impact bu discovers one imminent, naturally the top level of society would be evacuated (if physically possible within time frame) to safety, because global population preservation is impossible.
(c) government knows of non-ELE impact due and due to the nature of estimation, cannot predict the meteor's striking point, again with no defense against it, they would organise emergency meetings between governments to discuss prevention strategy, if that fails then (depending on when they discover ground zero) would evacuate populations as best they could.
All scenarios dictate that to preserve law and order, peace and civility, no fore-warning of mass destruction should be issued. And I agree with that policy. I don't want to see the world rioting and I don't want a countdown to my death. Ce la vie