His comments came after CCTV footage showing the fatal stabbing of bikie boss Pitasoni Ulavalu was played to the ACT Magistrates Court for the first time.

The video shows confessed killer Frederick Tuifua approach Mr Ulavalu from behind and plunge a knife into the Canberra Comanchero commander's neck during a melee at Kokomo's in Civic last July.

It was played on Monday as the first of the men to admit to his involvement in the fracas was sentenced to six months in jail.

The man, who cannot be identified because of court orders, pleaded guilty to an affray charge and was not accused of being responsible for Mr Ulavalu's death.

Agreed facts show the man, who is in his 20s, attended a birthday party with his co-offenders in Red Hill before the group made its way to Kokomo's.

One of them, Maximilian Budack, argued with a pair of Comancheros within minutes of arriving and the group left, but quickly returned.

Violence erupted when they reappeared, with punches thrown and items of furniture wielded as weapons as Mr Ulavalu tried to play peacemaker.

The man sentenced on Monday was captured on CCTV repeatedly punching Comanchero bikie Zachary Robb and kneeing him in the head.

He eventually left with the rest of his group, glancing towards where a fatally wounded Mr Ulavalu had staggered outside and collapsed on the road as he went.

The man was later filmed at Hopscotch in Braddon re-enacting parts of the fight with Budack and another of the offenders, Matthew Kupu.

On Monday, defence barrister Kieran Ginges said the man did not learn what had happened to Mr Ulavalu until later, having been unaware that any of the brawlers had been armed with a knife.

"He didn't know there was a serious altercation," Mr Ginges told the court.

"He thought it had been a bar fight."

Mr Ginges said the man had initially entered the fray in an effort to break the brawl up, but "testosterone" made him start launching blows.

He said the fight was prompted by "some mischief" with Budack's bag, which had been taken and "secreted" by the bikies during the initial argument.

"They were the sorts of issues that play out in children's playgrounds," Mr Ginges said.

He told the court his client had spent 64 days behind bars on remand, locked down for 23 hours a day during the first five weeks.

Mr Ginges said this was because police had "intelligence" that bikies and their associates had identified the man and made serious threats about him and his loved ones.

The court heard this had "torn apart" the man's family and forced him to move interstate once he was granted bail.

"My client lives in absolute fear of what may occur," Mr Ginges said.

Mr Ginges argued the man had already endured "significant punishment" and should not have to return to jail given the period spent on remand.

Prosecutor Luke Crocker said a jail sentence was necessary, but did not argue against any further time being suspended.

He claimed the affray was "aggravated by the death of Mr Ulavalu", and highlighted that the fight had taken place in a "crowded" venue where patrons were entitled to feel safe.

Magistrate James Lawton noted the "look of horror" on the faces of two women who were outside Kokomo's when Mr Ulavalu emerged and fell to the ground.

But he also observed some people inside the venue reacting very differently as the fight unfolded.

"I despair that we now live in a society where people get their phones out and film violence as a source of amusement ... instead of trying to break it up or calling the police," Mr Lawton said.

"It is depressing to watch that video."

Mr Lawton stressed that the man he was sentencing did not murder Mr Ulavalu, but he said anyone who took part in such public violence "should expect to go to jail".

He backdated the man's six-month jail term to include the time already spent in custody, and suspended the balance with a 12-month good behaviour order.

"There's no justification for this sort of behaviour," Mr Lawton said.

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