“A name of a man is a mind- numbing blow from which he never recovers,” notes a quote from Marshall McLuhan as this gobsmacking new documentary – a Grand Jury Prize winner at Sundance – opens.

With this in mind, perhaps seven-term US congressman Anthony Weiner ought to have chosen his pastimes more carefully. Many of his Capitol colleagues have engaged in more serious infractions than texting pictures of an erection in underpants, but Weiner's name ensured that his sexting antics would launch a thousand headlines: Thus, "Obama Eats Weiner!" according to the New York Post. And so on, until the very silly man resigned.

This extraordinary chronicle, characterised by extraordinary access and dozens of “No, really?” moments, offers a terrifying and cautionary tale of political hubris, as Weiner’s attempt at a comeback in the 2013 New York mayoral race resembles a slow-motion car crash. More accurately, the equal weighting of comedy and tragedy makes for a slow-motion Acme-brand car crash.

Prepare to rub eyes. Late into the documentary, one of the incredulous co-directors asks what the viewer has been pondering since the opening sequence: “Why in the world did you let us film this?”Weiner fails to mention self-delusion in his response. But in an era when a Tweet, never mind a week, is a long time in politics, Weiner is clearly banking on an electorate with goldfish memories.

Enter Sydney Leathers, a busty wannabe adult-film star with whom Weiner shared a correspondence. Cue backtracking: Weiner never put an exact number on all those groupies he was texting; he never put exact dates on when he was cruising online sites such as The Dirty under the name (wait for it) Carlos Danger.

Enter his wife, Huma Abedin – private aide-de-camp, confidante and “second daughter” to Hillary Clinton – who turns out amid the feeding frenzy to play stand-by-your-man at a press conference.

There are occasionally cracks in Abedin’s impeccable, unflappable, couture-wearing patina, as her disgraced husband soldiers on: “mirth of the damned” doesn’t begin to cover his toe-curlingly manic demeanour at a street parade in the days before the election.

While she can look exasperated, Abedin, like her boss, is a political animal. She allows her uncomfortable silences and FFS expressions to play out for co-directors Josh Kriegman, a former staffer, and Elyse Steinberg.

When Weiner’s equally exasperated campaign manager faces the paparazzi after a fresh round of revelations, Abedin snaps into professional wife mode.

“Quick optics thing. There are photographers outside. So when you leave, look happy.”