Hunter Lawrence Jonasen could be heard 'jeering and cheering' with Callum Gibson Mckenzie, 17, as they purposely ran over the animal on Christmas Day in 2015.
They were allegedly behind the video which showed the bloodied possum struggling under a car wheel until its entrails were hanging out.
Jonasen was not convicted over the incident but was given a probation order meaning he had to keep out of trouble for one year or he would be re-sentenced.
That order was due to expire next month but the 18-year-old found himself back in court on Friday for assaulting a man while on probation.
Holland Park Magistrates Court heard Jonasen punched a stranger in the face outside a nightclub so hard that part of the victim's lip was missing.
Ms Cornack said Jonasen was on 'trajectory' and needed psychiatric help.
'He's got a severe defect that the rest of the community needs to be protected from,' Ms Cornack said. 'He should have an order that he never own an animal. He shouldn't be near any dogs, cats or birds.'
Jonasen was sentenced to a new two-year probation order, banned from owning an animal for two years and ordered not to interfere with native wildlife.
That punishment was on top of another one-year probation order Jonasen was given for the assault in January 2017.
RSPCA prosecutor Tracey Jackson said the organisation was pleased with the outcome.
'Whether or not you care about animals, you need to care about animal welfare and about how our society and our community deals with it.'
Jonasen's defense lawyer claimed the teenager was 'extremely remorseful' for his actions, which would 'dog him' for the rest of his life.
(Daily Mail - April 28, 2017)