Caveat to anyone who hasn't seen the previous entries: These shows are the opposite of "in-depth." Apparently, the budget to clear clips is minimal, and so they use a limited number of them, often ones that aren't representative of the topic but seem to be only what they could afford, and then show bits of them repeatedly. They also tend to spend most of their time on the people who are willing (and still alive) to sit for interviews, at the expense of giving a balanced view.
Granted, by the fourth series, maybe they have more money to spend and are doing a better job on this front. But I bet the Closed Captioning will still be risible.