In the decades since Kurt Cobain took advantage of his Second Amendment rights, unauthorized documentaries about him have become a cottage industry to rival 9/11 Truthers, as a quick YouTube search for "Kurt Cobain" and "documentary" will demonstrate.A few documentaries have even played in theaters, though they were hamstrung by not being able to use Cobain's music or image beyond the confines of fair use. Enter Brett Morgen'sKurt Cobain: Montage of Heck, the first documentary made with the blessing of Cobain's estate. It makes use not only of Nirvana's music but also of Cobain's diaries, drawings, Super 8 films, and — most intriguingly — the sound collages from which the film takes its title. A snippet of one plays over the Universal logo at the beginning, a perversity Cobain probably would have appreciated. In addition to the usual talking-head interviews (although not with the Talking Heads),Montage of Heckuses every trick in the modern documentary book, including animating Cobain's voice recordings and private journals, thus ensuring every aspect of the intensely private man's life is laid bare in a way that straddles the line between celebratory and mercenary. At 132 minutes, however,Montage of Heckbecomes more of a marathon – never hellish, but occasionally overwhelming, which is no doubt the point.