Darnella Frazier's viral video of George Floyd's final moments showed the world what she happened to see and document on a Minneapolis street last May.

Last week, the world got a glimpse of the trauma that still haunts her because of it.

"There have been nights I stayed up apologizing and apologizing to George Floyd for not doing more and not physically interacting and not saving his life," Frazier testified tearfully during former police officer Derek Chauvin's murder trial. "But it's like not what I should have done, it's what he should have done," she said, referring to Chauvin.

Like Frazier, who simply happened to be taking her 9-year-old cousin to the store that evening, other people who have stumbled upon and documented instances of police violence describe recording as the only thing they could do in situations where they felt helpless. Often, they end up encumbered with guilt, sleepless nights and other mental health concerns.

The experiences witnesses described in court last week are consistent with symptoms of post-traumatic stress disorder, said University of Minnesota psychology Prof. Patricia Frazier. Though many people associate PTSD with combat, it can include witnessing many forms of death and threats.

"That qualifies as a trauma for PTSD. It makes sense that if someone was right there when it happened and filming it, that they would be experiencing trauma symptoms," she said.

Guilt and regret over not doing more to stop Floyd's death could be consistent with "moral injury," when someone feels guilty for not stopping an event that violated their moral code, the professor said.

The first week of testimony in the trial revealed that more people filmed Chauvin and three other former Minneapolis police officers than previously were made public.

High school senior Alyssa Funari, a minor at the time, was also recording that day.

"I felt like there wasn't really anything I could do," she said in emotional testimony. "As a bystander I was powerless there, and I was failing to do anything."

Afterward, Funari said she felt numb, pushing the experience aside because she did not know what to feel.

Ever since George Holliday captured on his new camcorder the 1991 beating of Rodney King by Los Angeles police, video has become integral in raising awareness of police violence across the country.

In 2016, Diamond Reynolds broadcast her boyfriend Philando Castile dying in the front seat of his car after he was shot by a St. Anthony police officer. Reynolds said it is always necessary to pull out your phone to get footage of incidents that could turn deadly.

"I didn't want to be accused of doing anything that caused Phil to get killed. I wouldn't have been able to live with myself if that happened," Reynolds said.

It's been difficult for Dae'anna, Reynolds' daughter, who was in the car that night, Reynolds said, adding that the fourth-grader continues to go to therapy.

"She loves leading protests. ... We want her to be a healer to other people who've gone through similar things that she has," Reynolds said.

When police approached Eric Garner and Ramsey Orta in New York City in 2014, Orta knew what to do. He'd been recording his interactions with police for about a year, uploading the videos to YouTube for accountability and his personal safety. But he didn't realize until months later how he had been affected by what he witnessed: his friend dying after an officer put him in a chokehold during an arrest.

"Mentally I wasn't stable, physically I wasn't right, I was losing a lot of weight, I wasn't sleeping," Orta said.

Without the support he got for filming the video, Orta said he is unsure if he would have recovered.

"I was always criticizing myself for not doing enough," Orta said, echoing the guilt witnesses expressed in Minneapolis.

Showing the world what happened to Garner continues to affect Orta daily, he said.

"As many times as I try to forget about this or keep my mind off it, either the TV, the radio or somebody around me or something that I look at just brings it up and brings it right back. I never get away from it," Orta said.

"I can't breathe" — the words both Garner and Floyd uttered as they lay dying, still disturb Orta.

"I'll be talking to somebody and they'll say, 'I can't breathe.' In an instant, that triggers," he said.

But filming these interactions with police can bring awareness to police brutality, which Orta discusses in the 2017 documentary "Copwatch."

The invention of video makes it more difficult to ignore or invalidate cases of injustice, said Danielle Kilgo, a professor at the U's Hubbard School of Journalism and Mass Communication.

"The portability and the affordability, the adoption of mobile technology really gave people a defense line, especially communities of color, to sort of prove what hadn't been believed by so many people before," she said.

The Dart Center for Journalism and Trauma typically provides resources for journalists and photographers who experience trauma, but the center's programs are easily applicable to anybody who has witnessed violence, Kilgo said.

"They want to bear witness to a tragedy, and they know they can't intervene. It's been traumatic for journalists, and it's equally traumatic for citizen journalists who are picking up that role," she said.

Reynolds said she and others pull out their phones because they want to have evidence and they want their stories to be heard, knowing that narratives surrounding police interactions can be manipulated.

"The nastiest and gruesomest thing is taking out a phone and recording somebody as they are being hurt. You want to try to help them," Reynolds said. "But if pulling out your phone is the only way you can try to help, then save yourself by pulling out your phone. Take deep breaths. Don't think about it. Press that button and let it flow."

Staff writer Reid Forgrave contributed to this report.

Zoë Jackson covers young and new voters at the Star Tribune through the Report For America program, supported by the Minneapolis Foundation. 612-673-7112 • @zoemjack