The shocking footage was filmed over the school holidays outside the Newmarket Swimming Pool on Broadway, a busy road with high volumes of both foot and vehicle traffic.
Police said in recent weeks there had been a sudden surge in bikes being stolen from public places across central Auckland.
Meanwhile, a 10-speed bike taken from outside the same swimming pool complex is still missing. A youth with a shaved head walks up to the parked bike, pulls a bolt cutter from beneath his jersey, cuts the lock and cycles off into the path of oncoming traffic.
Police say they do not know who he is.
Another person is seen using bolt cutters in full view of members of the public but runs off as a security guard walks over to him.
The final clip shows a pair of 16-year-olds stealing bikes from the stands outside the pool.
Police arrived just as the pair were riding off.
One youth gave himself up immediately but the other ran off. He was later arrested at the nearby Newmarket Train Station. Both have been charged with theft.
Police said it was a constant battle to prevent bike thefts and they needed owners to make it harder for criminals to succeed.
"What this shows is that sadly there are more than a few people out there who will take any opportunity to steal whatever isn't bolted down.
"It also demonstrates that even if you feel you're parking your bike in an area where lots of people are around, brazen thieves will not be deterred. Buying a solid lock that is not going to be snipped in seconds is the best way you can prevent your bike from being stolen," said acting Inspector Graeme Anderson.
He urged bike owners to record serial numbers and write contact phone numbers on bikes using special UV marker pens.
"The other challenge for us is that we're catching up with these people and recovering the stolen bikes, but often we have no idea who the bike belongs to.
"In many cases people aren't reporting that their bike has been stolen, as a result we have dozens of unclaimed bikes that we can't return to the rightful owners. If you record your serial number, or buy a UV marker pen and write your cellphone number on the bike, it means we can prove it's stolen, and get it back to you," he said.
A man has been charged with theft and is in custody. Police have made referrals to other government agencies over the welfare of two children.