If David Attenborough chose to cover this, the entire episode of would last no more than five minutes and that's on a slow day. Apart from the fact that it is eye-gougingly boring and includes almost no noteworthy cinematography, it also does a pathetic job of actually answering the question in its title.

They explain the premise again and again, probably due to the original airing with intended trailer breaks, but it just makes the "documentary" even more frustrating to watch.

One of the worst documentaries I've watched in years, and far short of the usual Nat Geo standards. Free YouTube videos are many times better than this.