Police have released video footage in an effort to identify a group of fence jumpers who trampled on a security guard at a dance music festival in Sydney last month.

The 29-year-old security guard had his spleen ruptured and suffered internal bleeding after he was trampled at the Listen Out music festival at Randwick on September 27.

Investigators released mobile phone footage showing a large group of people forcing their way through a fence during the festival, which was held at Centennial Park.

Police said they hoped the public could help identify members of the group.

"As the 29-year-old man was responding to the rush, he fell to the ground and a person landed heavily on his abdomen," a statement said.

"The guard was able to walk to a stage area before collapsing."

Police said they were seeking to speak to a man aged in his mid-to-late teens, about 183 centimetres tall and of Caucasian appearance.

Police said he had short dark brown hair and was wearing a long-sleeved green shirt or jumper, black shorts and black shoes.

Anyone with information is asked to ring Crime Stoppers on 1800 333 000.