Nick Broomfield is a really challenging documentary film-maker: he's either very brave or very foolish. I've watched many of his films, and they are always gripping. Sometimes the subjects of his films, usually rather dubious people, don't seem to deserve the attention he gives them, and my main gripe with Broomfield is that he lets himself become too much a part of the story he's telling. He often gets into shot, and the final film is often more about him and the trials of film-making than it is about the issues.
But I love documentaries, and from my own LD collection I would cite these as particularly good examples:
MICROCOSMOS - a stunning French documentary (no commentary, none needed) of the most amazing micro-photography of insects, etc.
MOON SHOT: The Inside Story of the Apollo Project - a 4-sided disc telling the same story as "The Right Stuff", only with real footage and the real people!
THE LAST PARTY - a personal documentary by Robert Downey Jr. on the parlous state of American politics. Sounds dull, but it ain't!
LOOKING FOR RICHARD - Al Pacino digging deep into the whole psyche of Shakespeare's Richard III in preparation for a theatre production. Again, much more fascinating than it sounds.
and, of course, THE BEATLES: ANTHOLOGY - better than its DVD equivalent (has different footage in places).
However, most of my laserdisc documentaries are movie based, and the best of these include:
THE UNIVERSAL STORY - Richard Dreyfus hosts,
HERE'S LOOKING AT YOU WARNER BROS. - hosted by a galaxy of Warner big names including Clint Eastwood, Steven Spielberg & Chevy Chase,
MGM: WHEN THE LION ROARS - a superb 4-disc boxed set hosted by Patrick Stewart, and
HOLLYWOOD MAVERICKS - a detailed look at the careers of Samuel Fuller, Sam Peckinpah, Orson Welles, David Lynch and many others who have operated outside the Hollywood mainstream,
and not forgetting, DOCUMENT OF THE DEAD - the ultimate look at George Romero's zombie trilogy and how he did it. Loads of inside info.
The beauty of these film-themed documentaries is that they are chock-full of clips of all the best movies. The MGM one is so comprehensive - it includes virtually every big film the studio made before it was sold to Ted Turner. My favourite, however, is the Universal documentary, particularly covering the early years when they were the pioneers of the golden age of horror. Wonderful!