NSW Greens MP Sue Higginson referred the video, which had been circulating on social media, to the state's law enforcement watchdog on Tuesday.
The Law Enforcement Conduct Commission is already investigating the conduct of officers on February 9, where a mass protest at Sydney Town Hall descended into violent clashes between protesters and police.
The protest, attended by thousands, was sparked by a state visit of Israeli President Isaac Herzog.
In the footage, a male police officer is heard telling his female colleague: "I f***ing pumped that c***" and "then I punched him in the head when he was down".
His colleague is heard laughing on the footage and replying "so funny" and "I saw that".
NSW Police said the force was aware of the footage, but declined to comment further due to the commission's investigation.
Ms Higginson, who was at the protests, said there was a mob mentality among the police officers on the night.
"Seeing the officers laughing and joking about it adds a whole new level of egregious reality," she told AAP.
Demonstrators were pepper-sprayed, arrested, beaten and shoved by police.
One video shared on social media showed a group of Muslim men leading a prayer before being ripped from their kneeling position and taken away by police, while another showed a man being repeatedly punched in the stomach by officers.
Ms Higginson said she also wrote to NSW Police Commissioner Mal Lanyon and Police Minister Yasmin Catley, calling for the officers in the video to be stood down.
"They certainly must not be on the beat or being able to knock on people's doors," she said.
"This is a massive deficit of trust."
A NSW government spokesman said it was important for the commission to be able to do its work.
"We have confidence in that process and will let it run its course," they said.
Dozens of people were arrested at the protest, but charges against them are being reviewed after the Court of Appeal ruled controversial restrictions in place at the time were unconstitutional.
The measures, rushed through NSW parliament after the Bondi massacre, allowed the police commissioner to make a declaration preventing residents from holding authorised rallies for up to three months after a terror attack.
This left protesters vulnerable to arrest for obstructing traffic or pedestrian movements if they marched through the streets.
The Court of Appeal in April found the laws impermissibly burdened the right to political communication.
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