A passenger whose aunt was racially taunted on a Sydney bus first tried apologising to her enraged abuser, only to become a victim of his anti-Asian ranting.

The man, who only wanted to go by his surname, Kim, has spoken about the terrifying ordeal on Easter Saturday, part of which was filmed by a passenger and uploaded to YouTube.

In the video, a middle-aged Caucasian man yells at Mr Kim and his Korean aunt about the Japanese bombing of Australia during World War II and calls them "f---ing bastards".

Before the camera started rolling, he yelled racist taunts such as: "Do you f---ing speak English?"; "Japanese c---s"; and "why did you come to Australia?"