It has taken 25 years to bring Warren Beatty’s “Reds” to DVD, primarily because the writer/director/producer/star had, what were for him, uncharacteristically conservative reservations about the new technology. The intervening years have paradoxically strengthened and weakened the argument for the merits of a film that probably could not be made today.

As Mr. Beatty points out in one of the “special features” accompanying this admirably produced disc, released today by Paramount Home Video, “Reds” was the last Hollywood movie shown in theaters with an intermission. Moreover, it’s a lavishly produced three-hour-plus epic about Bolshevik cheerleader John Reed, who died young. A blockbuster with brains, it’s a far cry from “Pirates of the Caribbean,” and it may well have cost more to make in constant dollars.

The aesthetic value of “Reds,” which garnered 12 Oscar nominations in 1982, are impeccable: stunning photography by the great Vittorio Storaro (who took home one of the statuettes), sensitive scoring by Stephen Sondheim, a highly literate script by Mr. Beatty with an assist from the orthodox Marxist Trevor Griffith, and wonderful ensemble acting by Diane Keaton, Mr. Beatty, the late Maureen Stapleton, and Jack Nicholson in one of his least mannered performances as the playwright Eugene O’Neill. The use of “eyewitnesses” in documentary-style interviews to create historical exposition for the story was a genuine innovation that lent moral seriousness as well as charm to the project.Any movie that manages to get the likes of Walter Lippman, Rebecca West, a very funny Henry Miller, Hamilton Fish, and Georgie Jessel together to reminisce about the good old radical days in Greenwich Village is worth the price of admission.

Stapleton, who won an Academy Award for her wonderful impersonation of leftist/anarchist Emma Goldman, is a particular standout: “Voting is the opium of the people in this country,” she growls in one memorable scene.”Every four years, it deadens the pain.”

And because Mr. Beatty, who won his own Oscar for Best Director, can be a shrewd storyteller, he made his romantically leftish politics float comfortably — not to mention commercially — in what was, in the end, an old-fashioned love story between the rabble-rousing journalist Reed (Mr. Beatty) and the author Louise Bryant (Ms. Keaton).

The latter is the real star here.Always a talented actress with remarkable range, Ms. Keaton is utterly persuasive as a radical feminist with a predatory sexual agenda and professional ambitions that greatly exceed both her abilities and her work ethic.Sexy, willful, insecure, and deeply in love with a man she views as a rival for the world’s attention, Ms. Keaton gave a performance for the ages, displaying the genuine movie star’s mysterious ability to be magnetic even when playing the most obvious head case.

Mr. Beatty also demonstrates a fine sense of the nuance of left-wing activity in the period covered by the film, which is roughly 1915 through 1920.The people portrayed are not single-minded political activists dedicated to the overthrow of elected governments, although there is ample evidence in the historical record, and even a hint in the film, that Reed, whose “Ten Days That Shook the World” glorified the Bolsheviks, fit in that category. At one point he admonishes Goldman for being willing to go to prison for her birth control agitation when her anti-war efforts were needed most. It is clear that this collection of writers, artists, and organizers were in business to remake their world, not just its politics.They wrote poetry and appeared in plays in Provincetown, and some swapped sexual partners in the name of freedom. One of Bryant’s thwarted projects was an analysis — three years late — of the famed Armory Show, which in 1913 introduced European Modernist artists like Matisse to shocked audiences in New York, Chicago, and Boston.

The problem with “Reds,” and the reason for its strange datedness, has nothing to do with art and everything to do with history. It was made eight years before the fall of the Berlin Wall and the collapse of the Soviet edifice. In 1981, the hard left could somehow rationalize the mass murder perpetrated by Lenin, the galloping anti-Semitism and, ultimately, the madness of Stalin. They could tell themselves there was no policy of deliberate starvation in Ukraine, that religious believers deserved to be marginalized or even persecuted, that the Gulag described by Solzhenitsyn was a literary invention or, at worst, exaggerated.

All this was possible as long as they could point to the Soviet experiment as man’s future and his destiny. The romance of radicalism depends on the end justifying the means. When that end is no longer attainable, all that remains is the bloodshed and the memory of ruined generations. What’s more, Mr. Beatty’s apparently diligent research on the period was completed without access to the Soviet archives, which now disclose what anti-Communists had long maintained — that Soviet communism not only enabled criminals but was in and of itself a criminal enterprise.

The clearest concessions the movie makes to emerging Soviet realities come in the form of Reed’s insistence that dissent is necessary to the Revolution and in the character of Gregory Zinoviev (nimbly played by the late novelist Jerzy Kosinski), who slaughtered plenty of people before he was himself murdered by Stalin in 1936. One is left wondering whether Reed would have lived to regret his association with the Bolsheviks. Max Eastman, played well by Edward Herrmann, and Rebecca West, appearing as herself, certainly had second thoughts about their earlier radical sympathies. But Reed, who died of typhus in Moscow in 1920, was never forced to confront the fact that his ideas had consequences. When he succumbed, raising political hell was still a pretty good time. As one of the “eyewitnesses” says of Reed, with no apparent irony, “It isn’t everyone who can be buried at the Kremlin.”

That is certainly true.