Footage shows a man talking to a woman outside a shop on Young Street in Frankston, at about 1pm on March 8, when they are approached by a third man carrying a metal pole.
The third man struck a 50-year-old Sandhurst man in the face with the pole.
He kept walking toward Park Lane after the attack.
He is not known to the victim.
The 50-year-old man was taken to hospital with serious but non-life-threatening injuries.
