It was a good doco. Plenty of real science and light on the hyperbole, although some of the numbers have been revised down as a result of the WISE survey.
[Spoiler Alert]
I was surprised (as I'd not heard of it before) but, in 2008 (?), a real asteroid was detected, computed to be on a collision course with Earth, with impact in 19 hours, and then tracked to impact with all the appropriate authorities informed along the way (e.g. "Mr President, it's NASA on the line. You're going to want to take this."). Luckily it was a small one, and it impacted in the middle of the Nubian Desert.
But, not to worry. There's only 20,000 or so near-Earth objects larger than 100m in diameter, and each impact would probably only be equivalent to a several-megaton warhead.
Actually, most of the potentially dangerous ones are thought to have already been found. But it's the ones they don't know about that worry me!
[/Spoiler Alert]
There were some quite nice night-scape pictorials in the background while a voice-over was going.
