A Victoria police officer was captured on video punching a teenager and calling him "stupid" before his partner demanded the recording be deleted, a jury has been told.

Melbourne police officers Simon Mareangareu and Dennis Gundrill are on trial in the County Court charged with unlawful imprisonment, attempting to pervert the course of justice and perjury over the incident.

Mr Mareangareu was also charged with intentionally causing injury for allegedly punching 17-year-old Kyan Foster, who was walking home with a friend in Melbourne's east, when he was approached by the police officers in the early hours of Christmas Day in 2014.

Both men pleaded not guilty to the charges.

Prosecutor Bruce Walmsley QC told the jury Mr Foster was sitting on a fire hydrant by the roadside as he spelt his name to Mr Mareangareu, when he was punched in the face.

"Kyan's knocked off the fire hydrant and the physical movement of Mr Mareangareu is over him and on top of him," he said.

"Shortly thereafter he's handcuffed … and as he will tell you, he was then face down in some asphalt.

"He recalls later in the night with a very badly bloodied nose … even gravel and asphalt in his nostrils," he said.

'Get rid of that video', policeman allegedly said

Mr Foster's friend, 16-year-old Stuart Laird, captured the incident on video on his mobile phone.

The footage was played to the jury and captures Mr Mareangareu telling the boys he suspects they've "been doing burglaries" before asking for their details.

After he allegedly punches Mr Foster to the ground, Mr Mareangareu can be heard shouting "you're not sorry, you're stupid, you don't listen".

Mr Gundrill can later be heard telling Mr Laird to "get rid of that video right now".

Mr Laird stopped the video momentarily but as he continued recording, one of the boys can be heard shouting "you can't twist my arm … get off my arm please".

Mr Gundrill later tells one of the teenagers that he is under arrest for "suspected burglary".

Mr Walmsley told the jury the boys were taken back to a police station in separate divisional vans and there were attempts made "predominantly by Mr Gundrill to secure the phone off him".

The court heard the teenagers had been smoking marijuana earlier that night and the police found cannabis in one of their backpacks.

Teen's father paid experts to recover videos

The jury was told the boys' parents were called and when Mr Laird's phone was returned to him by police "he discovered the videos had been deleted".

"He'll tell you he didn't delete them," Mr Walmsley told the jury.

"It was a guilty mind that deleted the video."

Mr Walmsley said Mr Laird's father later paid experts to recover the deleted videos and both were recovered.

Both boys were charged with possessing marijuana, assaulting and resisting police over the incident.

Mr Walmsley told the court the police officers involved made statements that they could smell cannabis on the boys and suspected they had committed a drug offence.

"That is opportunistically, after the event, fed into their false statements," he told the jury.

"If they could smell marijuana or had any sense that they were under the influence of drugs … how would you have got at the outset 'hey, you're suspected of doing burglaries', singularly?"

Mr Mareangareu was charged with attempting to pervert the course of justice for allegedly having an improper conversation with Mr Foster's mother when he was serving the charges against her son.

The police officer's defence counsel will address the jury on Friday.

The trial continues.