"He was verbalising that he wanted to stab me - he wanted to kill me.
"And often, you won't see the danger coming.''
The video then cuts away to footage of a man lunging at an ambulance officer helping a person on the ground.
Just seconds before, the man is seen standing nearby, looking around and acting seemingly normal.
"I can't save you if I'm having to save myself,'' the officer says.
The video ends telling people to: "Please, hands off our ambos.''
In the past year, ambulance officers had been assaulted - kicked, punched, spat at - and verbally abused nearly 3000 times, St John said.
About 10 attacks a month were so serious, staff had to be hospitalised and required ongoing medical treatment.
One paramedic had a bow and arrow pointed to their head.
Another officer had a knife held to him and was told that if the patient he was dealing with died, so would he.
Paramedic Roger Blume said: "It's pretty hard to concentrate in those circumstances.
"One patient attacked me, bit me and spat blood into my mouth.''
St John chief executive Peter Bradley said ambulance officers had simply had enough.
"We simply won't enter a dangerous scene. We will retreat and your mate or loved one won't get the treatment they need while our personal safety is at risk,'' he said.
"Ambulance officers are caring, non-judgmental professionals there to help but we ask the public to respect our profession."
The stats:
• Nearly 3000 crew abuses were reported in the year December 1, 2015, to November 30. (2695 incidents were reported but not all were captured before March 2015 because St John was moving to electronic reporting.
• About 70 per cent or 2000 cases of abuse against crew were verbal.
• Nearly 30 per cent of attacks involved some form of physical and verbal abuse. Six per cent involved just physical abuse.
• Of about 65 physical assaults reported each month, 6-10 are very serious.
• 50 per cent of all abuse involved alcohol or recreational drugs.
• 15 per cent of attacks involve patients with mental health issues.
• Most - 37 per cent - of the abuse happens between midnight Friday and noon Sunday.
• Most abuse and assaults happen in Auckland, Christchurch, Hamilton and the metropolitan areas.
• However rural and remote communities also involve risks (including more single crewing). The profile of the risk changes and the likelihood is lower but the consequences are higher.