A Brisbane man was charged earlier this year after he allegedly attacked a 14-year-old boy who he claims tormented his step-daughter.
Mark Bladen, aged 53, tracked the alleged bully down and confronted him at a skate park in Brisbane.
The firefighter yelled and pointed at the boy, before grabbing him by the neck and appearing to choke him, footage obtained by 7 News shows.
Recalling the event in a 60 Minutes preview ahead of this Sunday's full episode, Bladen revealed that it was the boy smiling that made him snap, according to UNILAD.
Describing the relentless way his daughter was bullied by his victim, he told the show:
Dr Jekyll came out.
His daughter added that the child who was choked in the video had called her names and given her insulting gifts
Bladen only stopped chocking the teenager when a friend of the boy's intervened, dragging the man back and yelling:
Get off him!
The boy - who suffered bruising to his throat and scratches to his limbs - reported the incident to the police, showing them photos of the alleged scuffle.
Bladen pleaded guilty at Brisbane Magistrates Court on 20 March to one count of assault occasioning bodily harm.
He was sentenced to pay $1000 (£543), with no conviction recorded after the court heard he had an exemplary history, and $500 (£272) compensation.
The father reportedly told police he was "aghast" with his behaviour and apologised to the victim outside of court. He said:
I'm very sorry for what I did, very regretful and ashamed.
Please don't do what I did, I just lost control. It's definitely not the way to handle things