The footage shows Athabasca Chipewyan First Nation Chief Allan Adam being floored and repeatedly punched by a Royal Canadian Mounted Police officer.
The confrontation took place in Fort McMurray, Alberta, on 10 March.
Protests demanding police reform have spread across Canada recently after spilling over from the US.
Although RCMP Commissioner Brenda Lucki initially said she “can’t say for sure” whether systemic racism is a problem with the police, on Friday afternoon she released a statement saying “systemic racism is part of every institution, the RCMP included”.
“Throughout our history and today, we have not always treated racialised and Indigenous people fairly,” she wrote.
Before the public release of the footage on Thursday night, the local RCMP division said they had reviewed it and found the officer’s actions “reasonable”.
The incident begins when an RCMP officer approaches Mr Adam and his wife over an expired licence plate.
The nearly 12-minute long video, recorded by a dashcam from the RCMP officer’s vehicle parked behind Mr Adam’s lorry in a casino car park, begins with Mr Adam having a heated and profanity-laden discussion with the officer.
“I’m tired of being harassed by the RCMP,” he says.
Mr Adam and the officer continue to have a heated argument. At about the 4:45 mark, the officer tries to arrest his wife, twisting her arm behind her back until she says: “Ow!”
That is when Mr Adam gets out again, shouting: “Leave my wife alone!” He pushes the officer away. Everyone gets back in the vehicle.
Backup is called, and Mr Adam gets out of the lorry. The officer begins to arrest him, and Mr Adam says “don’t touch me”, using an expletive. That is when a second officer runs at him full speed, knocks him down, and repeatedly punches him while shouting: “Don’t resist.”
The incident is being investigated by the Alberta Serious Incident Response Team, which oversees incidents involving police where someone is hurt.
Mr Adam told Canadian media: “Because we are a minority and nobody speaks up for us, everytime our people do wrong and the RCMP go and make their call, they always seem to use excessive force.
“And that has to stop. And enough is enough.”
Mr Adam’s lawyer Brian Beresh wants his client’s charges, which include assaulting an officer and resisting arrest, to be dropped. Mr Adam is next due in court on 2 July.
Mr Beresh has practised law for 44 years, and says police violence against indigenous people has been a constant issue.
“I’ve seen this from the first day I’ve started to practise,” he told the BBC.
“I’d like there to be some positive action taken by the RCMP, in terms of how they can prevent this from happening again. If this can happen with my client who’s a respected chief, what about the First Nations person who is living on the street, who doesn’t have my client’s standing?” (Courtesy BBC)