Black Power members and associates were in the outdoor area of Mac's Brewbar, when a Mongrel Mob group was refused entry, words were exchanged and a fight broke out about 1am in Stuart St outside the bar.
Footage of the incident, captured by the Otago Daily Times, shows several people fighting on the road and one man pinning another to the ground.
A SPS security guard wearing a hi-viz vest joins the fray and punches a man in the side of the head, continuing to throw punches along with another man, the footage shows.
The victim falls to the ground, where the guard continues his attack. He then appears to deliver one final kick - a reveller also kicks the man before the man on the ground hauls himself up and runs off.
Police arrived in a van shortly after and swarmed the scene, by which time the group had become more subdued. Police eventually arrested five people.
It is understood several Tribesmen Motorcycle Club members or associates were in the nearby Countdown car park preparing to come to the Octagon before police arrived there in force.
A police spokeswoman said a 33-year-old man was scheduled to appear in the Dunedin District Court on Tuesday charged with possession of methamphetamine and possession of an offensive weapon.
A 62-year-old man is also set to appear on Tuesday, also charged with methamphetamine possession, the spokeswoman said.
The remaining three people received written warnings.
Taimalie said two of his staff members were knocked unconscious by the man who was later captured on video footage being attacked by the guard, but was quick to say the guard's actions were unacceptable.
"That doesn't excuse his actions.
"He overstepped the mark."
He said he had spoken to the guard, a father who worked two jobs, and disciplinary action would be forthcoming, though the guard's "aggressive'' conduct was a result of seeing his two colleagues knocked down earlier.
"Those two guys have families - they're fathers.
"But I'm not trying to justify it - the force used was overly aggressive."
The use of force by security should be the bare minimum needed to protect the guards or others, he said.
Taimalie said the Octagon could contain thousands of people on a busy night and things could rapidly become volatile for security guards, who were regularly subject to abuse.
"It's ruthless, it's dangerous ... They get spat at, abused, called racist names."
Many problem revellers they encountered had pre-loaded on alcohol as well as taken drugs before coming to the Octagon, he said.
