"Our investigations into the incident are continuing and it doesn't stop when people have been arrested," Senior Sergeant Steve Sutherland said.
"We want to see as much footage as possible so we can identify those who took an active part in the riot."
Police have also been viewing videos posted on media and social media sites.
Footage on YouTube showed projectiles flying through the air, fires smoking, and young people clutching alcohol and jumping between a flattened divide that had separated the crowded campsites.
"It would be very helpful for our investigation to gather as much information ... and we hope those who hold that information will be able to assist us," Mr Sutherland said.
Police had also found evidence that suggested the violence had been preplanned on social media.
Tairawhiti area commander Inspector Sam Aberahama told Radio New Zealand that certain comments on social media indicated "there was going to be a breach of the fence between two camps". He said the troublemakers "had a plan and they were going to carry it out".
On Thursday, Gisborne District Council condemned the rioters and said it was "appalled" that a small group of mischief-makers was able to spoil what had been a well behaved and successful event.
In the face of huge pressure from festival-goers, event organisers had withdrawn their application for an on-site liquor licence that would have banned BYO alcohol.
But the council stated it was clear "those who were determined to make trouble would have done so no matter what the licensing arrangements".
"We will certainly be looking to ensure that the organisers that lease the land from us take every possible action to avoid this happening again," council chief executive Judy Campbell said.
Riot videos can be emailed to intel.eastern@police.govt.nz.
