A brilliant start to the 2019 season saw Walker make the New South Wales State of Origin side but a dud performance led to him being cut.
The Channel 9 sports reporter who broke the story, Danny Weidler, said that Rabbitohs CEO Blake Solly "had advised Walker to go to the police".
"I have spoken to people I trust who have seen the video and it shows Walker involved in a fight and kicking the man, who is standing upright, in the chest," Weidler said.
"A person says Walker's name, which is audible in the video."
The Rabbitohs play the champion Roosters in a glamour Sydney derby on Friday next week.