The other video displays a student throwing another one on the ground, repeatedly punching and kicking them whilst they lay on the concrete.
The grandparent also said the fights were within a week of each other.
Orewa College Principal Greg Pierce told Newshub he is aware of the video and its implications.
“The students involved in this incident are being dealt with appropriately for their actions by the college’s disciplinary processes and the police are involved in this process.
“This behaviour is in total contrast to the positive manaaki values of the college which the vast majority of our students reflect on a daily basis.”
Senior Sergeant Roger Small from Waitematā North Police told Newshub in a statement they are also aware of a video circulating online which depicts an assault at Orewa College this week.
“We are following up this matter with the school and are working to identify the parties involved so we can address the issue.”