This is an entertaining, informative, and even-handed look at the Earth's magnetic field, how it has changed over time, what it is doing now, and what it all might mean.
The computer graphics used are interesting and effective, but the most interesting part was the (previously unknown to me) magnetic history stored in volcanic rock. Some of the conclusions they draw from this work can really make you think.
Although documentary DVDs are usually not very cost effective, giving you a (if you're lucky) 1-hour program for the price of a 2-hour blockbuster movie, this one is worth a try. And as the Earth's magnetic field continues to change (it's clearly in the midst of a fast-moving decline right now), this could be a good source of entertaining info to review later.