Chauvin faces second and third-degree murder charges, as well as one charge of second-degree manslaughter.
The 46-year-old black man was later pronounced dead at a hospital.
Martin said Floyd appeared to be under the influence of drugs or alcohol while he was in the store but was "very friendly, approachable, talkative".
Hall told the New York Times last June that Floyd didn't resist the arrest and instead attempted to defuse the situation.
Mr Martin told the jury he had sold Mr Floyd a packet of cigarettes, and received a counterfeit note as payment.
Floyd then bought a pack of cigarettes with a $20 bill that Martin believed to be fake because of its blue color and texture. Another employee went on to call the police.
Mr Martin testified on Wednesday that he watched Mr Floyd's arrest outside with "disbelief - and guilt."
FLORIDO: And by he, she meant officer Chauvin, who was sitting just a few feet away from her in court.
On Wednesday, four police body camera videos and various surveillance videos were played for the jurors.
Mr Martin and co-workers went outside to a vehicle where Mr Floyd was sitting with two other people but they refused to return to the store and the manager called the police.
Mr McMillian said he remembers feeling "helpless" seeing the incident unfold. As Chauvin knelt on Floyd's neck and Floyd cried out for help, McMillian can be heard on video telling police to "get your knee off his neck". The bodycam footage was shown in court, revealing that McMillian did approach Chauvin after Floyd's death to tell him that he didn't respect what he did.
What else has happened in the trial so far?
The defence has argued that the now-fired white officer did what his training told him to do and that Floyd's death was not caused by Chauvin's knee on his neck, as prosecutors contend, but by a combination of illegal drug use, heart disease, high blood pressure and the adrenaline flowing through his body. She said that both Chauvin and fellow officer Tou Thao put their hands on their Mace cans to ensure the crowd wouldn't get close. The officer also asked twice if the officers should roll Floyd on his side, and later said he thinks Floyd is passing out.
FRAZIER: It's been nights I stayed up apologizing to George Floyd for not doing more and not physically interacting and not saving his life. Darnella. 3. Darnella's cousin. 4. When she noticed what was happening, she pulled out her phone to film.
"It wasn't right - he was in pain", she said. But the day started with someone who first took the stand yesterday, Donald Williams.
McMillian began sobbing as police bodycam video of Floyd's arrest was played, removing his glasses and wiping his eyes with tissues until Judge Peter Cahill called a brief recess.
Witnesses testified that no bystanders interfered with police.
Hansen, who is a trained emergency medical technician and Minneapolis firefighter, testified that upon taking in the scene, she moved closer to the officers who were pinning Floyd on the asphalt and identified herself as a first responder.
During a testy cross-examination, Chauvin attorney Eric Nelson pointed out that Williams seemed to grow increasingly angry at police on the scene, swearing at and taunting Chauvin as a "tough guy", "bum" and other names, then calling Chauvin expletives, which the defence lawyer repeated in court.
Why is this case so important?
A cashier who was one of the last people to speak with George Floyd alive last May testified at former Minneapolis policeman Derek Chauvin's murder trial on Wednesday that he regrets accepting the fake $20 bill that led to Floyd's deadly arrest.
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