CCTV footage of the Grevillea unit of the maximum security adult prison on February 13, the day of the riot, was shown to the Supreme Court on Thursday and released publicly on Friday, providing one of the first glimpses into the controversial youth justice centre.

The footage, requested by lawyers of children who argue that the unit is illegal, shows a riot starting in the communal area of the ground level.

One of the inmates is seen throwing a chair up towards a staff member as they walk downstairs towards them. As the staff member catches it, the inmate throws another chair at him, prompting a number of guards to emerge from the unit's control room.

A number of children appear to join in, throwing chairs across the unit towards guards, and overturning a large table. As some children run past the guards, they can be seen spraying them for extended periods of time with capsicum spray.

Lawyers for the children told the court that guards deployed capsicum spray about four times in the footage.

A number of inmates and staff not deliberately targeted with the spray appeared to be affected by it, with the footage showing many coughing, covering their faces with their T-shirts, and hunched forward or falling on to the ground.

One child covers his face with his T-shirt, while continuing to throw things in the guards' direction.

Another clip shows Security and Emergency Services Group officers wearing gas masks as they walk through the empty unit, strewn with overturned furniture.

Dr Ian Freckelton, QC, has said the unit is "incapable" of meeting the children's human rights under the law, with guards for the adult prison also working in the unit, despite not being trained to work with troubled youth.

He said a school was not able to be registered on the site, and that children and staff alike were exposed to capsicum spray through the ventilation system.

Richard Niall, QC, for the government parties, has said it was "not only just, but inevitable" that the children were moved after a riot at Parkville youth justice precinct destroyed more than 60 beds there.

Fairfax has previously reported that Victoria Police is investigating the riot, which allegedly involved about 16 inmates. Emergency staff and Department of Health and Human services took almost three hours to bring the centre back under control, with one Corrections Victoria staff member reportedly receiving a facial injury in the process.

Justice John Dixon, who is presiding over the latest legal challenge to the unit, became the second Supreme Court judge to visit the Grevillea Unit in person on Thursday.

Justice James Elliott previously visited the unit to help him decide a bail application for one of the young inmates. Justice Elliot said conditions for children there were "far from ideal", but did not rule on whether they breached their human rights.

The trial continues.