The co-director of the acclaimed "Lost in La Mancha" discusses Terry Gilliam, the art of documentary making, and watching "The Man Who Killed Don Quixote" fall apart.

You've had a lot of success in Europe, has there been a good reception to "Lost in La Mancha" in the US?

Yeah, but in the US documentary isn't viewed in the same way. I don't think they understand that it's more than just pointing the camera and the truth just gets recorded. I think there's a greater appreciation for the craft of documentary filmmaking here.

You must have shot a lot of footage, how was post-production?

It was awful. It was an eight-month period. We started by saying, "Right, what are the good scenes? What do we like?" but then just because you have this list of the 20 scenes that you like, doesn't mean that it's a story. You have to really work to massage a story out of the footage and come up with peaks, emotional highs and lows, and character strands and plot strands. It's a lot like writing a fiction script, except that you have a limited palette from which to draw from.

How did Terry Gilliam react to your film?

Terry was very supportive during the editing process. Normally you can expect when you show footage to your subjects, they say, "I don't like that shot of me, I think my hair looks awful in that shot." But Terry would look at it as a filmmaker and he would say, "You know I don't think you're getting enough humour of this particular scene" or "You're being too gentle here, you need to really go for the throat." He would analyse it as a fellow storyteller.

Do you and Keith film together?

We had one camera. I shot most of the film and a lot of the times it was just me in the room. We have this policy where it's never good when your documentary crew outnumbers the subjects, and a lot of the stuff was two people having an intense conversation. Keith would usually pave the way for me to get into the room, he would make the arrangements and cajole the right people into saying, "Okay, he can come in" and I would go in and shoot for however long it took to get that one tiny little kernel, that would be a minute of screen time.

Did anyone ever tell you to switch off the camera and get out?

It wasn't a very common thing. Part of the challenge of making a documentary is knowing when to back off. You need to be allowed to come back the next day, so you need to walk a very careful line in terms of, when is it too much? You need to know; now is the time that I should disappear, so that the people I'm shooting don't start to get self-conscious. But you know Terry sets a very good example, he says, "Trust these people, they're completely trustworthy. I'm comfortable with them in the room. You should be comfortable with them as well." And most people followed his example.

Terry mocks us for having to go to him and ask, "Do you want us to keep shooting?" He's like, "You were just whining and complaining and I had to tell you, 'Stop whining and complaining and get on with it'". Which is a little bit of an exagerration, but it suits him. When shooting stopped and we went back to Madrid, that was the moment when we said, "All right, we need to ask Terry how he feels about this." Because on the set as things were going wrong, there's a way that Terry laughs through everything and that laughter is usually a sign that it's okay to keep shooting. The big tip off for us was when Terry stopped laughing. Then you knew that things were changing emotionally, because he never stops.

What do you plan to do next?

We have a full bag of tricks. One of them is a small, very dark comedy drama, another one is a Gilliam-esque, sort of fantasy, freaked-out, trippy film. Keith has a very dark, sombre drama that he's written. And then we have this new documentary which we're persuing. It's a documentary about a secret scandal in the British music industry that we want to blow the lid off of.

"Lost in La Mancha" is now out to buy on DVD.