In the bystander's video the handcuffed Donovan Jackson, who is black, is seen being punched in the head by a white officer. He is then slammed into a patrol car.
The incident in 2002 was resonant of the Rodney King beating by Los Angeles police officers 14 years ago.
The city and Los Angeles county did not admit any wrongdoing in the tentative agreement, Albert DeBlanc said.
The family's lawyer could not be reached for comment yesterday.
Donovan, who suffers from hearing, speech and learning difficulties, was returning to his car after paying for petrol when the officers told him to drop the crisps he was eating and put his hands on the car.
A young white DJ staying at a hotel nearby heard the commotion and ran outside to record the beating. It was broadcast around the world.
The officer, Jeremy Morse said he had reacted forcefully after Jackson grabbed his testicles during an arrest at a petrol station.
The videotape did not show whether any grabbing occurred.
Mr Morse was sacked and his one-time partner Bijan Darvish was suspended for 10 days for filing a report which allegedly failed to mention Mr Morse's conduct.
A judge dismissed a criminal charge of assault against Mr Morse after two juries failed to reach a verdict.
In January a jury awarded $1.6m (£830,000) to Mr Morse and $811,000 to Mr Darvish, who sued Inglewood for discrimination, arguing that a black officer who allegedly hit Jackson with a flashlight received a lesser punishment.
Inglewood's black police chief, Ronald Banks, denied that race had been a factor in the punishments.
Mr Banks told reporters: "I based my decision on their actions and what I thought their responsibility was.
"It was based purely on the facts.
"I was shocked at not only the verdict but the size of the award. It was somewhat ridiculous."