I think we've reached that point where we understand medically what we are doing to ourselves with these sports. In football, it's kind of hard to get the access that you want for the story and, of course, it's very long-term: the effects of the repeat concussions really don't hit until decades afterwards, whereas the traumatic injuries in extreme sports are very immediate. I realized Traumatic Brain Injury was a fascinating and important story that not had been told very much. I wanted to know more.

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.

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.

Extreme sports tricks are becoming increasingly complex, the courses ever more challenging and crashes all too common.

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 love making fiction films as well as nonfiction ones, and hope to keep challenging myself to make better and better work.

I can't help seeing 'Waste Land' as the third in a triptych with my earlier films 'Devil's Playground' and 'Blindsight,' and not least in the awe and gratitude I feel for the group of people who were courageous enough to share their stories with us - and to live lives so rich in inspiration for us all.