Asked if the movie makes difficult viewing, Hetfield tells US radio host Elliot Segal: "Yeah -hearing yourself, watching yourself, seeing the mirror back at what other people see. Joe Berlinger and Bruce Sinofsky, the directors, ended up being pretty much fly on the wall, so you really kind of forget the cameras are there and you're being yourself.

"A lot of times I'm not really comfortable with myself, seeing myself in the situations. But, man, I learned a lot about what I don't like about me, which was good - and I think everyone involved pretty much felt the same way about themselves."