The video claims the child was left there to be scared into behaving.
It warns the most powerful Mexican cartels are now targeting us.
The road up Te Mata Peak was closed on Saturday due to an apparent patching ceremony.
Witnesses claim the gang members stopped anyone accessing the peak.
Tensions have been rising after the shooting of a gang kingpin.
He entered a not guilty plea to one charge.
They embraced and shook hands when reunited in the court dock.
Josh Masters is a charismatic leader with a lot of friends, gang researcher Jarrod Gilbert says.
A bullet reportedly hit the gang president's vertebrae.
Police say they've arrested another three people.
But he says more needs to be done to stop meth use in New Zealand.
It comes after assets were seized from Comanchero members in Auckland.
The Comanchero biker gang received help from white-collar pros, NZ Police allege.
Over $3.7 million in assets were seized in operation.
He accuses them of "raping, burglarising, selling drugs and having guns".
But others warn they won't be handing their weapons in.