The world of extreme sports is also one of the big businesses. Kids might think that snowboarding is the ultimate freedom, but this freedom is being marketed to them by commercial sponsors.

With portable cameras and affordable data and non-linear digital editing, I think this is a golden age of documentary filmmaking. These new technologies mean we can make complicated, beautifully crafted and cinematic films about real-life stories.

I am riveted by extreme sports like big-wave surfing, 'megaramp' skateboarding and half pipe snowboarding. I am fascinated partly because the sports are so exhilaratingly acrobatic. But I am also captivated by the fear that a terrible accident might happen at any moment. And accidents do happen.

I don't believe in objectivity. I observe the observer's paradox every moment I'm filming. Your presence is changing everything; there's no mistaking it. And you have a responsibility.

I have always been interested in garbage: What it says about us. What in there embarrasses us, and what we can't bear to part with. Where it goes and how much of it there is. How it endures. What it might be like to work with it every day.

I remember when the Berlin Wall fell and suddenly intractable problems get solved.

The world needs more women filmmakers, so we have to keep encouraging ourselves and one another, and eventually things must get easier for us.