This week, VH1, a network devoted in no small part to looking backward, offers the five-part documentary series 'Lords of the Revolution,' which begins Monday night, and a 40th anniversary look at 'Woodstock: Now & Then,' premiering Friday. (The latter will arrive on the History Channel on Aug. 17.) The admirably taut 'Lords' documentaries -- on Andy Warhol, the Black Panthers, Muhammad Ali, Timothy Leary and, surprisingly, Cheech and Chong -- seem somewhat educational in intent, primers directed toward viewers who weren't there or weren't paying attention if they were. The looser and less focused Woodstock film, although informative and fun, is, like most post-Woodstock Woodstock products, essentially a flattering portrait of what continues to be sold as a generation's defining moment. All that really links the subjects of 'Lords' is that they were instruments or reflections of cultural change in the '60s and '70s -- Warhol and Leary are polar opposites, and there is a long road to travel from the paramilitary rhetoric of the Panthers to the stoned repartee of Cheech and Chong. And the series does not provide a complete view of the subject: It might as easily have covered the Yippies, the Stonewall Riots and what used to be called women's lib. (There are no 'Ladies of the Revolution' here, apart from some of the women of the Black Panther Party, which does reflect the prejudice of the time.) What these films (and the Woodstock documentary) do have in common is that the people they are about and who appear in them have now attained their golden years -- each uses the effective device of placing a speaker before an image of his or her younger self. But though some have evidently mellowed, none recants the younger, wilder self. If there is not much of a critical eye applied to these controversial subjects, these are not mere hagiographies, either, and all do an excellent job of conveying a lot of information and atmosphere in entertaining short order. The Woodstock Aquarian Exposition is having a 40th birthday this month, and among the various commemorations is 'Woodstock: Now & Then,' directed by Barbara Kopple, an Oscar winner in 1976 for 'Harlan County, U.S.A.' and in 1990 for 'American Dream.' 'Now & Then' is a rather shaggy and diffuse film that, even though it contains much in the way of first-person reminiscence from people behind the scenes, on the stage and in the crowd and quite a lot of archival material, does a strangely poor job of evoking the time and place. Although an early talking head notes that there are two Woodstocks, the event and the myth, the myth is accepted more or less as fact. (Someone here calls it 'the seminal event of the century,' which is silly, even in musical terms.) Woodstock, as you will not learn here -- as if to protect its singularity -- was only one of several American rock festivals that summer. (Woodstock promoter Michael Lang, an executive producer of 'Now & Then' -- and the still charismatic star of Kopple's film as he was of Michael Wadleigh's 1970 documentary -- had in fact produced the Miami Pop Festival the year before, another fact absent from this film. ) The difference was the location -- the pretty countryside instead of a racetrack -- the number of people who came, and that, given the ratio of crowd to facilities, little went wrong. If anything, Woodstock is a testament to the organizational skills of an improvisatory counterculture. But it marked the end of an era, not its beginning. (On deck: Altamont.) Oddly, the best moments here take place not on Yasgur's farm but at the Paul Green School of Rock, where the young students are getting together a Woodstock-inspired program. Who fans get to the heart of 'My Generation,' an angry song from a band whose constitutional aggression was as far from the declared Woodstock spirit as could be. And a girl who'll be singing a Janis Joplin song gets closer to the contradictions of that age than does anyone else in the film. 'I hope that I'm channeling some part of her,' she says. 'Hopefully not the alcoholic, heroin-addicted part of her.' 