Adding to the challenge for social media sites, once original videos are pulled, different versions from downloaded or recorded copies start cropping up, and the never-ending cycle continues. Twitter and Google said they were working to stop the footage being reshared. Facebook did not immediately respond to additional questions.
The shootings in New Zealand show how the services they offer can be exploited by extremist groups, said Lucinda Creighton, senior advisor to the Counter Extremism Project. "Because if you do, sharing this video is exactly how you do it", Moore said.
"While Google, YouTube, Facebook and Twitter all say that they're cooperating and acting in the best interest of citizens to remove this content, they're actually not because they're allowing these videos to reappear all the time", Lucinda Creighton, a senior adviser at the Counter Extremism Project, an global policy organization told CNN.
The videos show the gunman driving to one mosque, entering and shooting randomly at people inside.
This is not the first time violence like this has been viewed on social media, despite efforts to prevent it.
In August, a shooting at a Madden 19 video-game tournament in Jacksonville, Florida, was captured on live video. "There were three in the hallway, at the door leading into the mosque, and people inside the mosque", he said.
He said the company condemned "the actions of these frightful persons and their disgusting use of our app for these purposes. That's unacceptable, it should have never happened, and it should have been taken down a lot more swiftly".
New Zealand's Department of Internal Affairs said people posting the video online risked breaking the law.
"The content of the video is disturbing and will be harmful for people to see", the department said.
"We're also removing any praise or support for the crime and the shooter or shooters as soon as we're aware", Facebook said.
But private online communities dedicated to violent content were still looking for ways to share copies of the video.
Britain's interior minister, Sajid Javid, said on Twitter, "Enough is enough".
And Twitter said it removed an account that was said to be linked to the suspect.
Portions of the video were also spreading by individuals on Twitter, which said it, too, was working to remove the content and had suspended the shooter's account.