In 1968, as the summer political-convention season approached, ABC News decided to take a gamble. The network seemed permanently stuck in third place, and its news division in particular suffered from the lack of a brand-name on-air authority figure to compete with Chet Huntley and David Brinkley at NBC or Walter Cronkite at CBS. Back in those days, the two leading networks covered the conventions live from beginning to end. (Can you imagine?) Instead of comprehensiveness, ABC went for provocation and at least the illusion of intellectual heft, hiring Gore Vidal and William F. Buckley Jr. to conduct a series of debates during the Republican circus in Miami and the subsequent Democratic debacle in Chicago. “Best of Enemies,” Robert Gordon and Morgan Neville’s lively new documentary, an accessible assemblage of archival footage and talking-head analysis, mines the Buckley-Vidal skirmishes for nuggets of historical insight.

And also — not quite the same thing — for zingers and gotchas and other flashes of that mysterious, you-know-it-when-you-see-it phenomenon called “great television.” The most memorable such moment occurred late in the battle, as the Chicago Police Department rampaged in Grant Park. What looked like law and order to Mayor Richard J. Daley and like “Gestapo tactics” to Senator Abraham A. Ribicoff of Connecticut set off a series of especially nasty personal volleys between ABC’s designated intellectuals. Vidal needled Buckley, calling him a “crypto-Nazi” until Buckley lost his patrician cool and snapped back: “Now listen, you queer. Stop calling me a crypto-Nazi or I’ll sock you in your goddamn face and you’ll stay plastered.” Ratings gold.

The filmmakers build to this moment as if it were D-Day or the Rumble in the Jungle, excavating a biographical Before and adumbrating a news media After. The smeary, hot hues of old video — the ’68 conventions were the first to be broadcast in color — add both immediacy and distance. Some protocols and artifacts of network television look quaint: the antenna-bedecked headsets of correspondents on the floor; the scripted prose of their reports. And the two antagonists, with their upper-crust accents and their compulsive displays of erudition, are not the kind of guys you see much on the tube these days, or anywhere else for that matter.

Buckley and Vidal were remarkable characters, at once bona fide intellectuals, true-blue aristocrats and knowing caricatures of those very types. Each one had, earlier in the decade, run a losing campaign for elective office in New York State: Vidal earnestly sought a congressional seat in the Hudson Valley in 1960; Buckley staged a lively protest candidacy in the New York City mayoral election of 1965. They were scions of powerful, privileged families, prep school graduates (Vidal never went to college), military veterans and tirelessly entrepreneurial men of letters happy to dabble in mass media when it suited their needs. They also genuinely and sincerely hated each other’s guts.