George Floyd's struggle with three Minneapolis police officers trying to arrest him, seen on bodycam video, has been shown in court at the trial of one of the officers.

The footage included Mr Floyd's panicky cries of "I'm sorry, I'm sorry" and "I'm claustrophobic!" as the officers tried to push him into the back of a police SUV.

At one point, Mr Floyd bucks forward, throwing his upper body out of the car.

Officers eventually give up, and Mr Floyd thanks them - and is then taken to the ground, face down and handcuffed.

Officer Derek Chauvin's knee pins his neck, another officer's knee his back and a third officer holds his legs, with the officers talking calmly about whether he might be on drugs.

"He wouldn't get out of the car. He just wasn't following instructions," officer Thomas Lane was recorded saying.

The officer also asked twice if the officers should roll Mr Floyd on his side, and later said he thinks Mr Floyd is passing out.

Another officer checked Mr Floyd's wrist for a pulse and said he could not find one.

The officers' video was part of a mountain of footage and witness testimony in Chauvin's trial on murder and manslaughter charges over Mr Floyd's death, showing how his alleged attempt to pass a counterfeit 20-dollar note at a neighbourhood market last May escalated into tragedy one video-documented step at a time.

A security camera scene of people joking around inside the store soon gave way to the sight of officers pulling Mr Floyd, who was black, from his SUV at gunpoint.

The extended bodycam footage gave jurors the fullest view yet of the roughly 20 minutes between when police first approached Mr Floyd's vehicle to when he was loaded into an ambulance.

When Mr Floyd was finally taken away by paramedics, Charles McMillian, a 61-year-old bystander who recognised Chauvin from the neighbourhood, told the officer he did not respect what Chauvin had done.

"That's one person's opinion," Chauvin could be heard responding.

"We gotta control this guy 'cause he's a sizable guy... and it looks like he's probably on something."

Mr Floyd was 6ft 4in and 223 pounds, according to the post-mortem examination, which also found fentanyl and methamphetamine in his system.

Chauvin's lawyer said the officer is 5ft 9in and 140 pounds.

Chauvin, 45, who is white, is charged with murder and manslaughter, accused of killing Mr Floyd by kneeling on the 46-year-old's neck for nine minutes, 29 seconds, as he lay face down in handcuffs.

The most serious charge against the now-fired officer carries up to 40 years in prison.

Mr Floyd's death, along with the harrowing bystander video of him gasping for breath as onlookers yelled at Chauvin to get off him, triggered sometimes violent protests around the world and a reckoning over racism and police brutality across the US.

As Mr Floyd was pinned down by Chauvin and other officers, Mr McMillian could be heard on video saying to Mr Floyd, "You can't win" and "Get up and get in the car".

Mr Floyd replied: "I can't."

The defence has argued that Chauvin did what he was trained to do and that Mr Floyd's death was not caused by the officer's knee, as prosecutors contend, but by Mr Floyd's illegal drug use, heart disease, high blood pressure and the adrenaline flowing through his body.

Events span out of control earlier that day soon after Mr Floyd allegedly handed a cashier at Cup Foods, 19-year-old Christopher Martin, a counterfeit note for a pack of cigarettes.

Mr Martin said that he watched Mr Floyd's arrest outside with "disbelief - and guilt".

"If I would've just not taken the bill, this could've been avoided," Mr Martin said, joining the burgeoning list of witnesses who expressed a sense of helplessness and lingering guilt over Mr Floyd's death.

Mr Martin said he immediately believed the 20-dollar note was fake.

But he said he accepted it, despite believing the amount would be taken out of his pay by his employer, because he did not think Mr Floyd knew it was counterfeit and "I thought I'd be doing him a favour".

Mr Martin then second-guessed his decision and told a manager, who sent Mr Martin outside to ask Mr Floyd to return to the store.

But Mr Floyd and a passenger in his SUV twice refused to go back into the store to resolve the issue, and the manager had a co-worker call police, Mr Martin said.

Mr Martin said that when Mr Floyd was inside the store buying cigarettes, he spoke so slowly "it would appear that he was high".

But he described Mr Floyd as friendly and talkative.