[Warning: The video below contains graphic content that viewers may find disturbing.]

The video shows a tiny, dark figure leaning off the side of Idaho’s Perrine Bridge. The sky above is gray, the Snake River rumbles 500 feet below. The figure, 73-year-old base jumper James E. Hickey, leaps from the bridge and his parachute bursts into flame.

“What the hell?” a spectator behind the camera says, half shocked, half chuckling. “We gotta —”

But as the distant fireball plummets toward the river below, it’s clear that something isn’t right. The laughter dies.

“S—,” someone else says, sounding frightened. “Oh s—.”

The video, which surfaced online Monday, gave investigators new understanding of how Hickey died beneath the bridge in Twin Falls, Idaho, earlier this month. The Perrine Bridge is a famous spot for base jumping — leaping off a high-up structure and deploying a parachute midair — and hundreds of people jump off of it each year. Injuries are common there, and last week a jumper had to be rescued when her parachute caught on one of the bridge’s supports.

But Hickey took an already dangerous activity and made it even riskier. Officials told the Twin Falls Times-News that Hickey intentionally set his parachute on fire, intending to disconnect it after a few moments and then deploy a second one that would carry him safely toward the ground.

“It’s my understanding that he was performing a stunt,” Capt. Brent Hilliard of the Twin Falls County Sheriff’s Office told the Times-News.

A base jumper hangs from her parachute on supports of the Perrine Bridge on May 12 in Twin Falls, Idaho. The bridge is a popular spot for base jumping, but injuries are common. (Stephen Reiss/Times-News via AP)

Along with extreme climber Dean Potter, who was killed in an accident at Yosemite National Park this weekend, Hickey is one of five people to die while base jumping this month. That statistic ties this May for the third deadliest month in the sport’s history, according to a fatality list compiled by BLiNC, a Web site devoted to base jumping. In total, BLiNC reports 256 fatalities since the sport was popularized in the early 1980s — and half of them happened in the past seven years.

[Extreme climber dies in Yosemite base jumping accident]

The recent deaths have put a renewed focus on the dangers of base jumping — an activity that veteran Hervé le Gallou described as “more like a suicide than a sport” in an interview with the New York Times. (Le Gallou died during a jump in the French Alps in 2012). Hickey and Potter made it even riskier: Hickey lit his parachute on fire, Potter was attempting to sail through a narrow “notch” in the cliffs over Yosemite Valley.

Online, critics questioned why anyone would risk their life this way. “I take it he had a death wish?” one Twitter user wrote of Potter.

But Temple University psychologist Frank Farley says that’s the wrong way to look at it.

“They don’t have a death wish; they have a life wish,” he told the Los Angeles Times. Farley has spent decades studying extreme athletes and risk takers — people who climb Mount Everest, drive race cars, sail across oceans alone in a tiny boat — and helped coin a new personality classification for these people. He calls it “Type T” — where “T” stands for “thrill.”

“You can look at these people and say, ‘They are stupid,'” Farley said in a 2006 interview with the Pittsburgh Post-Gazette. “I might say, ‘That is their personality.'”

As Farley explained it to the Chicago Tribune, “Type T” personalities require a higher level of stimulation to “get revved up” than the average person, driving them to take greater and greater risks. These thrill seekers can become athletes and adventurers or “mental risk takers” like artists and scientists, but they are always optimistic, charismatic and confident. So confident that they often don’t even consider what they’re doing a risk.

“They’ll say, ‘I’m not taking risks, I’m an expert,'” he told the LA Times. “… They don’t want to die and they don’t expect to die”

Erik Monasterio, a former base jumper, mountaineer and psychologist at New Zealand’s University of Otago, believes that the “Type T” personality manifests at a chemical level. In a 2012 study on base jumpers, he found that extreme athletes may have a lower level of circulating dopamine, a neurotransmitter that is released during risky activities and causes feelings of satisfaction or pleasure. That’s what drives them to seek out more and more dangerous experiences, he told the New York Times.

Fear is part of it too, Farley added.

“People will tell you, when you’re at the edge of danger, that’s when you really feel life,” he told the LA Times. “This is what being alive is for them. They don’t want to sit at a desk all day.”

That analysis certainly jibes with base jumpers’ own description of their sport.

“If you can’t comprehend it, it seems crazy,” Mark Knutson, who compiles BLiNC’s fatality list, acknowledged to NBC Bay Area after Potter’s death.

But “for us, we all know we’re going to die,” he added. “The biggest fear is not living our lives.”