Police and guards were caught on camera stripping, and beating man just outside the Cape Talk building in Cape Town in Somerset Square, Highfield Road.
The video shows police dragging a man out of his car, and pulling his pants down.
One of the officers then repeatedly punched him in the stomach. The same officer then kicked the man.
One of office workers watching the proceedings pronounced the situation "f***ed up."
"Police brutality! That's not how you treat a person" Nicole Speelman, who posted the video on Facebook yelled as the cop kicked the prisoner again.
"Why are you kicking him? Why are you kicking him? That's the only reason why you are in the news all day!" She yelled.
According to a Facebook post by Nicole Speelman, "The policeman came upstairs and banged on our door. He came to arrest me for screaming out the window. He arrested my colleague for interfering and the charges were later dropped.”
"What was even more disturbing is that police aggressively manhandled, pushed, choked, punched and kicked him repeatedly," said a DA lawmaker Dianne Kohler Barnard.
South Africa's police are frequently embroiled in allegations of brutality, yet prosecutions rarely occur.
The country's Human Rights Commission recently voiced concern at the continued use of force by the country's police amid a string of allegations of brutality recorded in the past months.
"People living in South Africa are tired in living in fear of both criminals and a handful of thuggish police officers," said the DA's Barnard.
South Africa's police force has come under intense scrutiny since shooting dead 34 striking platinum miners in August 2012.
Police watchdog the Independent Police Investigative Directorate (IPID) was not immediately available to comment on the most recent incident.
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