Fakhir Berwari – or “Crazy Fakhir”, as the Americans dubbed the Kurdish Peshmerga colonel – did some of the deadliest work on the planet. Without robots or blast suits, he disarmed thousands of mines; first in the aftermath of the second Gulf war, then, after a layoff enforced by the loss of his right leg, during the reconquest of Iraq from the Islamic State. The latter was more dangerous: Isis packed abandoned houses with IEDs in entranceways, under rubble, inside furniture. We see the colonel teetering from fatigue, but always ready to go the extra mile. “Fakhir knew he was the fastest and the most experienced,” says Hogir Hirori, director of The Deminer. “If he didn’t do it, then many more people would die.”

The Deminer makes for nervous viewing. Each of the four detonations we see ratchets up the sense of inevitability. It’s not quite a snuff movie, though haunted by a similar balefulness. What moral responsibilities do documentary-makers have when their subject is a danger to himself?

With Berwari, the film-makers seem in the clear; it seems certain the colonel would have carried on regardless, whether or not a camera was present. So, as with Restrepo, Last Men in Aleppo, Armadillo, Point and Shoot and other recent works sticking their head above the parapet in the Middle East, the prime responsibility for the film-makers would appear to be safeguarding the crew. Berwari always made the ultimate call on whether filming was OK, says Hirori. “Working with him always felt safe. His decisions about whether a situation was safe could always be trusted.”

Ethically, The Deminer is also affected by the fact that Berwari had begun documenting himself, as part of an attempt to archive his work for educational purposes. So it falls into the category – like the 2015 mountain-climbing ordeal Meru and many extreme-sports films – where the film-makers in jeopardy are on the screen. Which largely exempts them from the documentarian’s unspoken rule of care: not to exploit, goad on or unduly put subjects under duress. Not everyone passes: 2006’s The Bridge, a film about Golden Gate suicides, earned a black flag when its director, Eric Steel, chose not to inform family members later interviewed that footage of their relatives’ deaths would be part of the film (itself a highly contentious choice).

Still, the omnipresent camera trained on the Golden Gate’s rust-red guard-rail, waiting for loiterers, left uncomfortable questions about our role watching such moments. The same uneasy feeling, that we are somehow implicated, hangs over The Deminer. The camera is not an obvious colluder or coaxer that may betray its subject – such as in The Act of Killing, Borat or Capturing the Friedmans – but we are still emotional participants. With no first-person interviews and little personal or cultural background other than what is gleaned from scenes with Berwari’s family, The Deminer doesn’t chip away much at why he takes such extraordinary risks.

Without this deeper understanding, the film’s hair-trigger mechanics come close to enabling a voyeuristic experience, like a real-life Hurt Locker. Hirori suggests this non-reflective approach is true to the environment in which the colonel had to operate: “That is the way reality is in conflict areas. You don’t have the time to think: ‘Should I be doing this? Is this worth it?’ You just act.”

On the other hand, Hirori excised material that might have given his film stronger insight into Berwari’s almost absurdly selfless diligence: an interview with the colonel was cut because it didn’t fit with the decision to structure the piece around Berwari’s son, Abdullah, discovering the first cache of video material. Hirori also removed a strand showing Abdullah following in his father’s footsteps. “He was teaching Abdullah to disarm mines from a very young age,” says Hirori, “Once Fakhir realised that the situation was far worse than he thought, he made a decision [Abdullah] couldn’t come.” Hirori says it pulled the focus away from Berwari, but it could have deepened our understanding of ideas of duty in Kurdish patriarchal society, and whether Fakhir had a martyrdom complex.

Such questions about context, which weigh on all documentaries, press heaviest when a work has to pass judgment, or act as an epitaph. Werner Herzog’s Grizzly Man is another documentary in which the director had to decide how to frame a footage-cache overspilling with courage-cum-foolhardiness. Its subject, Timothy Treadwell, was a compulsive talker, and Herzog opts to press fearlessly into the far terrain of Treadwell’s psychology. Above all, Treadwell is aware of the camera. “It was [Treadwell’s] instrument to explore the world around him, but increasingly it became something more,” says Herzog. “It started to scrutinise his innermost being, his demons, his exhilarations. Facing the lens of the camera took on the quality of a confessional.” Becoming the custodian of Treadwell’s tale, he never forgets the camera’s complicit hold, making it visible in the story as he shapes the bookends of Treadwell’s tale.

Portraying characters on the edge, it’s up to every director to decide if the greater obligation is to the subject or the audience. The line that marks where a documentary should stop is fuzzy, often vanishingly so. In the defence of The Deminer – a film undeniably the product of great physical bravery – it must be even harder to locate in war.

• The Deminer is out in the UK on 27 April.