The Supreme Court of Victoria has released footage of a group of men as they set about preparing for a planned terrorist attack at Melbourne's Federation Square at Christmas time in 2016.

Key points: Abdullah Chaarani's father said he was "embarrassed" and "shocked" by his son's actions, the court heard

Abdullah Chaarani's father said he was "embarrassed" and "shocked" by his son's actions, the court heard The court was told Chaarani had tried to sign up for deradicalisation programs after his arrest three years ago

The court was told Chaarani had tried to sign up for deradicalisation programs after his arrest three years ago He said he now renounced the Islamic State group and its extremist ideology

The video was released as Abdullah Chaarani, 29, gave evidence at a plea hearing for himself and two others, Ahmed Mohamed, 27, and Hamza Abbas, 24, who were found guilty of terrorism offences last year.

Two of them have apologised for their actions and renounced the Islamic State terrorist group, which was the inspiration for the plan.

Chaarani told the court today he was sorry for his role in the plan to use machetes and homemade explosive devices to attack people in the CBD square over the 2016 Christmas period.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 11 seconds 11 s Ahmed Mohamed and Hamza Abbas are seen in a chemist and hardware store buying items to use in the attack.

The CCTV footage shows Chaarani walking in the driveway of his house, carrying a large machete in his hand, after earlier disposing of wrapping for the knife in a large wheelie bin.

Other footage shows Mohamed and Abbas making purchases at a chemist and Mohamed at a hardware store buying chemicals and other materials to make explosives to be used in the attack.

Mohamed is also seen placing items in the boot of his car at the hardware store and then driving off.

Plotter told 'you are not my son'

Giving evidence today, Chaarani told Justice Christopher Beale that he now renounced the Islamic State group, also known as ISIS.

"I renounce violent jihad. I renounce ISIS. I renounce extremist ideology," he told the court.

Chaarani also told the court even if he had not been arrested, he would not have actually followed through on the planned Christmas 2016 attack.

The court heard he had tried to sign up for deradicalisation programs in prison when he was arrested almost three years ago, but could not take part until his court proceedings were completed.

Federation Square is in the heart of Melbourne's CBD and regularly hosts music, performance and film events. ( ABC News: Jacqui Peake )

Chaarani told the court of being visited by his father in prison in the months after he was arrested in late 2016.

The court heard his father told a handcuffed Chaarani: "You've embarrassed me. You've shocked me. You are not my son."

Chaarani admitted he had been radicalised by watching videos of the Islamic State group.

Trio face potential life sentences

Yesterday Mohamed also took to the witness stand to reject the terror group.

He also told the court he had tried to engage in prison deradicalisation programs when he was first jailed but was also told he could not be part of the program.

Chaarani and Mohamed have sought to shift the blame to Ibrahim Abbas, who was jailed for 24 years for the plot last year.

Mohamed gave evidence yesterday that he had tried to get Abbas to pull back from the Federation Square plans.

Hamza Abbas, the brother of Ibrahim, will also be sentenced for the crimes, which potentially carry a life sentence.

Ahmed Mohamed, Abdullah Chaarani and Hamza Abbas were found guilty in November 2018. ( Supplied: Jeff Hayes )

Chaarani and Mohamed were also convicted this year of burning a mosque in Fawkner just weeks before the Federation Square plot was disrupted.

They are currently serving a 22-year sentence after a jury found them guilty of terrorism offences.

During the mosque burning trial, Chaarani's lawyers argued he had set the premises alight to protest against Shia Islam but that it was not terrorism.

The Imam Ali centre was a Shia mosque.

When he was found guilty in that trial, Chaarani yelled out to jury members but later submitted a letter of apology to Supreme Court Justice Andrew Tinney.

The trio will be sentenced on November 29.