“Mistaken for Strangers” documents National lead singer Matt Berninger, left, and the band. The only problem? His brother Tom, center, might be too close to the subjects. (Abramorama)

The best thing about “Mistaken for Strangers,” a new documentary about the band the National, is that you don’t have to be a fan to enjoy it. In fact, it helps if you’re not an admirer of the group’s moody, monotonous sound because, as much as the film hews to typically admiring rock-doc footage of its subjects, it also sneakily portrays them as prone to the preening self-seriousness that makes indie musicians such risible cliches.

That “Mistaken for Strangers” dances along that tightrope so deftly is surely because it was made by Tom Berninger, who, as the younger brother of National lead singer Matt Berninger, suffers from the complex amalgam of pride, envy, resentment and affection one might expect from the striving sibling of a rock star.

In 2010, the National was embarking on the biggest tour of its career; Matt, who grew up in a prosperous family in Cincinnati, invited Tom — nine years younger and, in terms of self-presentation, worlds away from Matt’s cooler-than-thou demeanor — to come along as part of the road team. (In the big-budget comedy version, Matt would be played by Aaron Eckhart with a five o’clock shadow; Tom, without a doubt, would be played by Zach Galifianakis. Get on it, Hollywood!)

The twist is that, as Tom confesses early in “Mistaken for Strangers,” he’s not a big fan of the National. He prefers Judas Priest. He also has some long-buried issues with his brother that inevitably come to the fore during their sojourn in Europe, heightened by the fact that Matt’s four bandmates also happen to be brother duos. What might have been just another anodyne promo piece or solipsistic valentine instead becomes a funny, eccentric and finally deeply poignant depiction of art, family, ­self-sabotage and the prickly intricacies of brotherly love.

Even with its fascinating psychological subtext, “Mistaken for Strangers” rewards fans with plenty of footage of the National performing, as well as some priceless Spinal Tappish moments between the bumbling Tom and his hip but somberly businesslike employers. (Trying to lure the band’s drummer into partying with him, Tom shares his observations about Matt and the rest: “They seem so coffeehouse and you seem so metal.”)

Once the band returns stateside, the plot thickens and the film opens up, with Tom interviewing their parents about how different he and Matt were as kids, and revealing more about the National’s tough early years. (“Mistaken for Strangers” has benefited from co-editing by Matt’s wife, Carin Besser, and the expert guidance of executive producer Marshall Curry.) With its tight running time of just over an hour, “Mistaken for Strangers” saves the very best for last, in a triumphantly moving final sequence that somehow explains everything there is to know about two guys who, despite radically different temperaments and tastes, always have each other’s back.

★ ★ ★

Unrated. At West End Cinema. Contains brief, mild profanity. 75 minutes. This movie was reviewed March 28 as a Video on Demand.