A court in Shanghai has heard via a video clip how bungling thugs allegedly hired by a district government to demolish the house of an elderly couple discussed robbing them of their valuables while they were tied up for 30 hours.

The district government claims the video clip has been altered, while the couple's lawyer said it was submitted directly to the court.

The couple, Liu Guangjia and his wife, Zhu Rongzhou, both in their 70s, is suing Minhang district government for 289 million yuan ($48 million) for alleged forced and illegal demolition of their house at Changning district court, also in Shanghai. 

Liu had built up a private museum next to his home, which included a bonsai garden of around 4,800 square meters and a collection of artifacts he had built up over 40 years.

In the video clip presented in court, the demolishers are heard chatting about taking the couple's belongings, including "valuable bracelets and jade."

According to the trial report the court posted on Tencent Weibo, the district government claimed during Thursday's proceedings that the clip had been edited by the plaintiff and could not be authentic.

However, the video was shot by staff from the public notary office during the demolition and provided by Minhang government as evidence of the legitimacy of the demolition. This is done according to China's regulations on preserving evidence of demolition dating from 1993.

The couple's lawyer, Hu Jiongming, said the district government had forgotten to check the audio when the video was submitted to the court.

"The most valuable items are lost," Hu said. According to the record in the public notary office, no property was listed in Liu's 582-square-meter home, or in the adjoining museum. The museum contained items he had collected over the past four decades, including dinosaur fossils and calligraphy. Gold, jewelry, cash and jade were missing from the house. 

Hu said the court only saw part of the video. "If the district government releases the full video of the demolition, they will find more problems during this demolition."

The couple were taken in a car and tied up in a shabby room for 30 hours after they tried to resist the demolition. Zhu had just finished treatment for breast cancer and Liu's arm was dislocated in the struggle, the trial report said. When they were released, the house, museum and all the contents were all gone.

The district government had originally given Shanghai Xiaoyu Real Estate Company approval for a new residential development in 2006. 

Prior to the demolition of the house in April 2012, the couple had failed to reach agreement over compensation with the developers. They had been informed of the intention to demolish in 2009.

The trial continues on Friday, said Hu.