Laura Poitras, left, and Glenn Greenwald accept the award for Best Documentary Feature for “Citizenfour” at the Oscars on Sunday at the Dolby Theatre in Los Angeles. (John Shearer/Invision via Associated Press)

“I’m a little concerned, the more we focus on that, the more they’re going to use that as a distraction,” world-famous whistleblower Edward Snowden tells filmmaker Laura Poitras and journalist Glenn Greenwald in “Citizenfour,” Poitras’s documentary about Snowden, which won an Academy Award on Sunday night. In that scene, shot before Snowden went public, Snowden is concerned about the mass media’s obsession with personalities.

In particular, he’s worried about whether coming out as the source of a huge cache of documents about American surveillance operations would detract from the content of those files. Whether Poitras intended it that way or not, “Citizenfour” is a testament to how necessary personalities and personal experiences can be to political reform.

“Citizenfour,” which aired on HBO Monday night, is a dispatch from deep inside Poitras’s and Greenwald’s deposition of Snowden — Poitras filmed their 2013 meetings with him in Hong Kong — and it doesn’t always bridge the gap between the reporters’ experiences and a more general audience’s.

“To see it, the physical blueprints of it, and the technical expressions of it, brutally hits home in a super-visceral way that is so needed,” Greenwald says of one document. I’m sure that’s true for him, given his deep absorption in the details of American surveillance. But if you’re not steeped in the story the way Greenwald is, the bolts from the blue aren’t as obvious. And while long scenes of anti-surveillance activists contain some powerful insights, they also add to the sheer volume of information in a way that can be more overwhelming than clarifying.

To Poitras’s credit, part of the power of “Citizenfour” comes from the way the movie juxtaposes mundane facilities with the malignancy carried out inside of them. “We are building the greatest weapon for oppression in the history of man,” Poitras reads from Snowden’s communications over shots of a bland construction site. The movie has a droning score that evokes the hum of servers. We see still shots of green fields punctuated by satellite dishes, Menwith Hill station in the United Kingdom with its Epcot-like domes, Dagger Complex in Germany, which comes across as an office park with bad lighting and slightly better security.

But the most powerful parts of the movie are the ones that show the surveillance state in action. Greenwald talks Snowden into coming out in part to provide a political rationale for his actions, but what’s done to Snowden has more impact than anything he actually says. During their meeting in Hong Kong, the fire alarms begin to go off, and it’s striking to watch Snowden and Greenwald tense, wondering if the alarms are a benign test, or an effort to flush them out for arrest. (It turns out to be the former.)

Snowden’s affect is muted, but even his tone can’t conceal all of the strain he obviously feels when he acknowledges that “I don’t think I’ll be able to keep the family ties that I’ve had for my life.” He’s proved right: his girlfriend Lindsay Mills (who now lives with him in Moscow and appeared on the Oscar stage on Sunday) is interrogated. “I just heard from Lindsay, and she’s alive, which is good, and free,” Snowden tells Poitras and Greenwald, revealing the full extent of his fears only in that expression of relief.

He even shows some wry humor about the pettiness of attempts to make his life more difficult. “My rent checks are apparently no longer getting through to my landlord, so they said if we don’t pay them in five days, we’ll be evicted, which is strange,” Snowden explains. “Because I’ve got a system set up that automatically pays them.”

Later, we get another brief, stark illustration of the exercises of power surveillance makes possible when Greenwald’s partner David Miranda was detained at Heathrow airport while transporting documents related to the Snowden stories. The fear and relief in Greenwald’s voice when he embraces Miranda, and Miranda’s eagerness to get away from the observing eyes of the cameras, say more about what we lose when we’re stripped of our privacy than even the most explosive document ever could.