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.

I find titles the hardest thing. I was worried that 'Waste Land' was too much of a downer. For me, 'The Crash Reel' confronts what the film is about: it's not just about the reality of a crash, it's about the extremity we all face, and what happens when life crashes on you.

My main trick is to work with amazing people. It's a long and twisty journey and you need people that really are amazing and have this rare gift of honesty and courage and really open up.

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.

I love great locations in movies, and I couldn't believe I'd never seen a landfill on screen before. It was the most haunting place.

I can ask someone to let me into all aspects of their life for several years, but people have got to have that gift: that courage and that talent for opening their lives to the camera. Being candid is a gift, and that's what the audience responds to. Part of it is me asking, and part of it is just their inherent talent, which is what you are looking for when you make documentaries - people that are really going to let you in on what they are going through.