What's not seen is what happened just after he stopped recording: Demint says three officers tackled him, took away his smartphone and then tried, unsuccessfully, to erase the video. They then arrested him on charges of obstruction of governmental administration and resisting arrest.
"I am 100 percent innocent," the 20-year-old Long Island college student told reporters earlier this month. "I didn't do anything wrong. I was just there to videotape."
Civil liberties experts say Demint is part of a growing trend of citizen videographers getting arrested after trying to record police behavior.
It's a backlash that comes as smartphones have made it easier than ever to make such recordings, which have become key evidence in high-profile cases of alleged excessive force, including the shooting of a fleeing suspect by an officer in South Carolina, the dragging of a Baltimore man into a police van, and the chokehold death of a New York City man on a Staten Island sidewalk.
"By all accounts the situation has gotten worse," said Chris Dunn, associate legal director of the New York Civil Liberties Union. "People are more inclined to pull out their phones and record, but that is often met with a very bad response from police."
Mickey Osterreicher, general counsel of the National Press Photographers Association, said he hears of "almost four incidents a week" in which police either harass, interfere or arrest citizens — not journalists — for shooting video. He notes this is occurring at the same time many police departments are deploying body cameras on officers.
"There is no reasonable expectation of privacy on either side," Osterreicher said. "Citizens can record police and police can record citizens when either is out on the street in a public place."
What makes the situation hard to define, civil libertarians say, is that no one is ever arrested on a charge of recording police because that has widely been upheld as protected under the First Amendment. Instead, they are being hauled into court on obstruction, resisting arrest or other charges.
A North Carolina man who says he "kept a safe distance" last spring while recording police taking his friend into custody at a bar was nonetheless booked on resisting and obstructing an arrest, charges that were later dropped.
A month earlier in Missouri, a man claimed he was arrested after recording the police response to a small protest outside the Ferguson Police Department. He says that as soon as he took a step onto a street that was blocked by police, he was booked on a disorderly conduct charge.
In some cases, the arrests are costing taxpayers money.
Earlier this year, the city of Portland, Maine, paid $72,000 to settle a lawsuit by a couple who were arrested after they filmed police questioning a suspected drunk driver.
In New York, a freelance videographer arrested after a Long Island police sergeant ordered him to stop recording the arrest of a suspect settled a federal civil rights lawsuit last year for $200,000.
Demint is also considering a civil case against police, who accused him of being combative and refusing to obey officers' orders to get back when he was arrested last year. His case is still pending.
Chief Kevin Fallon, a Suffolk County police spokesman, declined to comment on Demint's case specifically but said: "Video is certainly here to stay and people have a right to take video. But they don't have a right to interfere."
Jonathan Turley, a law professor at George Washington University, said the right to take videos of police encounters in public is clearly protected by the First Amendment. He said the trend is for police to detain people who are shooting video, and subsequently drop the charges.
"Exercising this right has consistently and uniformly been upheld by state and federal courts; they have made it abundantly clear that citizens have right to film police in public," he said. "What is alarming is the degree to which police are ignoring this clear precedent and continue to threaten citizens."
The NYCLU has been fighting back with an app that automatically uploads citizen videos to a central server as soon as a video is recorded, preserving the evidence even if the smartphone is seized.
More than 35,000 New Yorkers have downloaded the app since its launch in 2012, leading to tens of thousands of video submissions. And 17 ACLU affiliates around the country have adapted the app for their communities.
Earlier this month, California Gov. Jerry Brown signed "The Right to Record Act," which declares people may not be prevented from recording the police, provided they do not interfere with the officers performing their duties.
State Sen. Ricardo Lara said the legislation "reinforces our First Amendment right and ensures transparency, accountability and justice for all Californians."
"At a time when cell phone and video footage is helping steer important national civil rights conversations, passage of the Right to Record Act sets an example for the rest of the nation to follow."