When documentary filmmakers Joe Berlinger and Bruce Sinofsky (''Brother's Keeper,'' ''Paradise Lost'') were invited to film Metallica in the studio and in group-therapy sessions in 2001, they knew the film -- originally planned as a promotional video -- would be unusual. But when singer-guitarist James Hetfield stormed out one day, eventually ending up in rehab, the filmmakers realized they were faced with a golden, if bittersweet, opportunity. ''It's a classic ethical dilemma,'' says Berlinger. ''From a human standpoint, you feel bad. From a creative standpoint, you're like, 'Great scene!'''
Even after Hetfield returned and began readjusting to seminormal life, the shooting never stopped, and three years, 1,600 hours of footage, and $4.3 million later, the result is ''Some Kind of Monster,'' a startlingly intimate look at a veteran metal band in midlife crisis that created a mosh pit of major buzz at Sundance and other film festivals this year. ''It puts these guys on the same level we're all at,'' says Sinofsky. ''They have the same problems with their wives, children, work, and partners.'' What's even more jarring than scenes of arguments and shrink-supervised confessionals is that the band -- who officially own the film -- approved its release. ''Bruce and I still marvel at the access and lack of restrictions we got,'' says Berlinger. As for why the musicians would allow themselves to be seen in such an open-wound way, the codirector says, ''As cheesy as this sounds, this is a deeply spiritual film about human growth. Through guys who have a reputation for being the exact opposite, it's a very caring film. If it was the Dave Matthews Band, I don't think it would be as compelling.''