When you look at almost every submarine movie, to some degree or another, there's this 'Moby Dick' element, this Ahab element to them.
It's nice to stretch in different directions and use different muscles. You can get swallowed into Hollywood, where it's all about bums on seats and how commercial a film is.
When you see how people in the developing world react and how they use a camera, you realise how narcissistic we are and how the filming of ourselves and thinking that we're interesting enough to care about is odd.
You can go to places in Africa and Asia and find Marley graffiti. In the slums of Nairobi, you see his lyrics painted on walls, and you realise he has this almost religious significance to the underclass of the world. He's a guy born in a hut with no bed, and now he's probably the most listened-to artist in the world. It's fascinating.
The Internet has meant that advertising has migrated; there are hardly any classifieds in newspapers any more because they're all online. If people have a car to sell, for example, they sell it online; they don't go to the newspaper.
I'm not particularly ethnically Scottish; I have one grandfather who is Scottish, although he's called Macdonald, and you don't get a lot more Scottish than that. The Scottish part of my family are from Skye, and I've always been very aware of that - always been very attracted to Scottish subject matter, I guess.
I think the parallels of a giant power with overwhelming military superiority and might, with America and Rome, it seems obvious to me.
I've fallen out very badly with some of the subjects I've interviewed, because they see their lives a certain way; to step into a cinema and see your life depicted in another way can come as a terrible shock.
I suppose making documentaries is like doing journalism on film.
The first documentary I saw that tried to show the actual experience of being a soldier in combat was 'The Anderson Platoon,' by French director Pierre Schoendoerffer, which won the Oscar for best documentary in 1967.
Although 'The Anderson Platoon' was what we would now call an 'embedded film' - with all the ambiguities that term implies - somehow Schoendoerffer got away with showing things as they really were from a grunt's perspective.