3 Minutes Still The Champ
I still think three minutes gives the best overview of the impact threat with some other documentaries filling in the gaps. This new one (Fireballs from Space) has a much more detailed focus on a few more recent developments such as a South American Impact and NEAR. The NEAR based Eros videos alone are reason enough to watch this new documentary. 3 minutes still gives the best overview of potential diversion scenarios.
Siberian Explosion explains both what is known about Tunguska, what is unknown, and how several long term mysteries were solved.
Regards,
Mark