Former National Party MP and police detective Ross Meurant told hundreds of Head Hunters members inside the gang's headquarters to mobilise in a bid for political representation.
Failure to do so would leave those in gang communities as a marginalised underclass who would eventually turn to terrorism, he said.
The gathering would once have been unthinkable for both sides - Meurant was once a police inspector and told the gathered gang members how he had faced them down at Auckland's Westward Ho pub more than 30 years ago.
Meurant made reference to Sir Rob Muldoon, who built such a good relationship with gangs through developing work programmes that he became a patron of Black Power.
"Muldoon did recognise there's a big group of you guys. And if we don't do something - this is the third or fourth generation - in my view we are breeding our own Isis."
Meurant said he had spent a lot of time in the Middle East and Syria and had watched anger create chaos.
"Whatever it took, the ignition happened and we have the chaos they have over there. An underclass, for whatever they were denied, exploded.
Meurant ran through a list of controversial police cases when talking to the crowd. He was one of the officers who came up empty-handed when first searching the Crewe murder scene in 1970 - only to have the famously-planted cartridge casing emerge later.
He told the gang it was among events that showed him the police were a club that would band together.
He said the wider gang community in New Zealand was about 200,000 people and it would be enough to organise and win political representation.
Meurant said he wasn't urging all to become politicians but to ask where the power in the country lay and to consider what power they had and could have.
"What have you been doing in the past and where does the future lie?"
In the video, Meurant gets up in front of the crowd, gave a small chuckle and begins: "All right fellas," he started. "It's been a long time since I faced a group of Head Hunters."
He then told them his appearance there didn't mean they were friends and made it clear he disapproved of anti-social and criminal behaviour associated with gangs.
In an interview, Meurant told the Herald on Sunday he had been through many life changes since and had come to believe the answer to gangs was to bring them closer into society rather than keep them as an "underclass".
He was highly critical of Labour's approach to gangs, outlined by Police Minister Stuart Nash and reported exclusively in last week's Herald on Sunday.
Meurant called it "banal and childish" as it appeared to be vote-grabbing "eradicate gangs" politics when gangs had existed for thousands of years. It was policy "pandering to a conservative, ignorant category of New Zealanders" and would achieve little.
Instead, he said jobs and a voice in society was the way to take offending out of gangs.
Meurant said the meeting came about after a coincidental meeting with Head Hunters president Wayne Doyle, currently the focus of benefit fraud charges and under pressure through asset seizures led by police.
Once he accepted, word went out to those who were Head Hunters or associated with the gang, prompting hundreds to attend the talk at the east Auckland headquarters.
Assistant Police Commissioner Richard Chambers said the cases Meurant referred to had been well traversed through the courts, and all police shootings were the subject of "multiple comprehensive investigations".
"I find a number of Mr Meurant's comments bizarre and ill informed. Mr Meurant has not worked for NZ Police for over 30 years. The organisation has undergone significant change in that time, both in our internal culture and in the way we police in our communities."
Black Power member Denis O'Reilly said there was a difference between gangs and organised crime and was concerned the new Government's policies didn't understand that.
He said inclusion was the way to deal with the problems that existed inside gangs.
O'Reilly, also a social activist and consultant to government, said the anger of the underclass that had been created "turned inward" but was vulnerable to outside influence.
"But if you were al Qaeda or Isis, that's where you'd target. Look at where Isis is targeting in France."
Security services in Paris have struggled to counter radicalisation in the city's poor suburbs where unemployment is rife.
"If you can't win at one game, you go and play another."
Nash did not return calls. Police headquarters was preparing a response around Meurant's appearance at the gang headquarters.
National police spokesman Chris Bishop said "gangs need to change their approach to society" if they wanted to enter the mainstream.
He said "everyone was in favour of jobs and getting involved in the community" but not if it meant gangs continuing selling drugs and being connected to organised crime.
Meurant left the police at the rank of Inspector and went on to serve three terms in Parliament. Even after leaving Parliament as an elected official, he remained working for NZ First through the late 1990s and into the 2000s.
Since then, Meurant has developed an international business career and is also the Honorary Consul for the Kingdom of Morocco.
He has embraced National Party politics again and has been reported as being on the electorate committee for Papakura MP Judith Collins. Meurant has a picture of himself with Collins' husband, David Wong Tung, in Morocco together.
Collins said Meurant wasn't - as had been reported - on the committee. Instead, she said he was an "active party member" who "has a role but it's a very small role".
His views were not her views, she said. "They couldn't be any more different."