Footage of the incident allegedly showed a confrontation between a group of teenagers and police, including officer Ryan Barlow, at Ward Park in Surry Hills in June 2020.
The boys refused to give their names, claiming they were doing nothing wrong before one of them mouthed off to the male constable.
The teenager allegedly said: “I’ll crack you in the f—— jaw, bro”.
Barlow can be heard telling the teenager to turn around and put his hands behind his back before he appears to kick the young man’s legs out from beneath him and handcuffs him face down on the ground.
The filming person can be heard yelling: “You just slammed him on his face.”
The teen was treated in hospital for injuries to his knee, shoulder and face, including a chipped tooth.
Today, the teenager told the court his threat to the officer was hollow and said in frustration.
“I can’t go to my own park and not be harassed by police,” he said.
The teen said he can’t remember much after hitting the ground.”I was unconscious,” he told the court.
He denies accusations he was trying to kick Barlow’s groin during the arrest.
Barlow has pleaded not guilty to an assault charge, with a magistrate to decide whether the use of force was by the book.
He was grilled by his own colleagues and in a recorded interview claiming the teenager was trying to resist.
The prosecution said the phone and body-worn videos will prove otherwise.
An expert in officer training is expected to give evidence about the take-down technique, which is not taught to NSW Police but is not banned.