Mr Bo's former police chief and right-hand man Wang Lijun also submitted written testimony which suggested he was well aware of the $US3.2 million French mansion, paid for by billionaire Dalian businessman Xu Ming, at the centre of the case's main bribery charge.

But Mr Bo angrily dismissed Mr Wang's statement as "bullshit".

In an 11-minute video recorded on August 10 and played in court on Friday, Gu Kailai looked nervous, spoke in a soft voice, and had her hands tightly clasped together in front of her on the desk for virtually the whole duration of the interview.

Wearing a casual black-and-white striped top and sporting short cropped hair, she looked thinner than her previous public appearance during her trial for the murder of British businessman Neil Heywood.

When quizzed about whether Mr Bo was aware of the largesse from Xu Ming, she hesitated to provide a certain answer – initially saying "he should have known" given the close relationship the businessman had with the family.

Asked if she had told her husband directly about Xu Ming's money, she first said "I guess it counts as though I've told him", before giving a more definitive "yes, I told him", when probed further.

But Bo Xilai angrily contested her version of events, saying that Gu Kailai after becoming "insane", had been pressured by investigators to implicate him.

"How much of her testimony is credible?" he said. "Gu Kailai's changed, she's gone mad and always lies."

But in the video, Gu Kailai laughed when asked if she had been coerced in anyway in giving her statement.

The court on Friday, which restricted access to public but provided detailed transcripts via its official microblog account, heard in great detail about Neil Heywood's involvement with the family before his death in November 2011.

Testimony heard from witnesses Gu Kailai, Wang Lijun and French architect Patrick Devillers also helped paint the fullest picture of why Neil Heywood was ultimately murdered.

Gu registered a company in 2000 with Mr Devillers to buy the six-bedroom villa in the French Riviera, with a view to secure the financial future of, Gu Kailai and Bo Xilai's son, Bo Guagua.

Gu, wanting to distance herself from the company, transferred her half of the company to Neil Heywood in 2007.

But by early-2011, Heywood and Gu had began to fall out, and Gu wanted to transfer the 50 per cent share to the girlfriend of Xu Ming to manage.

Mr Devillers said this prompted Heywood to demand 1.4 million pounds or he would "expose everything".

"I've never seen Neil so angry before," Mr Devillers said. "He was saying he was lied to and was fooled by her."

It was during this period that Gu said she began to fear for her son's safety, which ultimately led her to murder Heywood on November 15, and in turn set in train China's worst political scandal in a generation.