Former Cosatu general secretary Zwelinzima Vavi and EFF leader Julius Malema are plotting to overthr.
Tatane died after he was shot during a confrontation between the police and residents of Meqheleng in Ficksburg, Free State, protesting over service delivery.
Rose Tatane has been supported by her late husband's cousin Madieketseng Nthodi during the court proceedings.
Before the video was viewed, the packed courtroom was ordered to behave.
The widow had been warned earlier by prosecutor Sello Matlhoko about the sensitivity of the video's contents.
She was told that the footage could be painful to watch.
Tatane's cousin Nthodi was overcome with emotion. She could not contain herself and stayed outside the courtroom.
The video was part of three that were going to be used as evidence in court. The first video was compiled by the SAPS, another by the SABC and the third one by Meqheleng Concerned Citizens which Tatane was a member of.
In the footage, former Setsoto local municipality mayor Mbothoma Madona is being verbally abused by thousands of protesters.
Community leaders attempt to bring the crowd to order, but instead residents demand the removal of Madona.
On April 13 last year, Tatane was among thousands of Meqheleng residents who flocked to the municipal building demanding better service delivery.
The video shows pandemonium breaking out with people running for cover as the police open fire with rubber bullets.
They later return and chant slogans.
Tatane is seen in a confrontation with the police. He takes off his T-shirt. He is walking bare-chested with his T-shirt in his right hand.
Six minutes later, a group of police charged at him. They surround him and severely assault him with batons.
They hit him on his back and front. A minute later, he stands up bleeding from his chest.
Three men rush to him and assist him as he cannot walk properly. He then falls down.
A minute later, an emergency vehicle arrives next to Tatane whose upper body is lying on a friend.
"How can you shoot him at such close range? How can you shoot a person like that?" shouts a man among those gathered next to Tatane before he is certified dead. Police are nowhere near him.
Policemen Nicodemus Israel Moiloa, Mothusi Magano, Solomon Moeketsi, Mphonyana Ntaje, Jonas Skosana, Isaac Finger and Olebogeng Mphirima have all pleaded not guilty to Tatane's murder.
The case continues today.