The video has an unnerving first-person view. A man walks across a parking lot. Two people are standing in a doorway when he shoots at them with a semiautomatic gun. One falls while the other tries to crawl away.

The black-and-white clip was uploaded to Facebook. It was a partial recording of a livestream by the man who killed 51 people at two mosques in New Zealand.

The video has been on Facebook for more than three years. The text pops up about three-quarters of the way through the video, urging the audience to share it.

The man accused of killing 10 people at a Buffalo grocery store said that he drew inspiration from the New Zealand shooting. The clip on Facebook, one of dozens that are online, even after years of work to remove them, may have been part of the reason that the shooter's tactics were so easy to emulate.

More than 50 clips and online links were identified by The New York Times in a search over the course of 24 hours. They were on at least nine websites and platforms, according to The Times review. Three of the videos had been uploaded to Facebook as far back as the day of the killings, according to the Tech Transparency Project, an industry watchdog group.

The clips and links were easy to find, even though the platforms pledged to eradicate the footage in 2019. Tech companies and governments formed coalitions to crack down on terrorist and violent content online.

The Times found this week that a mass killer's video has an enduring afterlife on the internet, despite the fact that Facebook expunged 4.5 million pieces of content related to the attack in six months.

Brian Fishman, a former director of counterterrorism at Facebook who helped lead the fight against terrorism, said that it is clear some progress has been made since the tragedy in New Zealand.

People have added watermarks or filters to alter the clips of the attack in order to outwit some of the large platforms that rely on artificial intelligence to take down toxic content. Others started posting the web addresses of the videos instead of directly uploading the clips to avoid detection by the same software that matches shooting videos to previously known versions. Some people uploaded the videos to less popular hosting platforms.

The Buffalo attack is likely to persist on the internet if the Christchurch footage is any guide. The shooting spree was broadcast for less than two minutes before it was cut off by the company. It was enough for someone to record the bloodshed and for links to that recording to spread widely.

The links have appeared on several websites. According to experts and a review by The Times, videos of the Buffalo attack have also been uploaded to Facebook, and other sites that are popular with right-wing users.

Many of the sites said they were working to remove the links and clips to the Buffalo killings so they weren't as popular as the clips from the Christchurch shooting. Even if the Buffalo footage on mainstream platforms reduces significantly, it would never disappear from the internet, according to the U.S. representative to the international.

According to Facebook, for every 10,000 views of content on the platform, an estimated five were of terrorism-related material. The videos from New Zealand violated the rules of the two websites and they were removing them. Telegram did not respond to requests for comment.

On March 15, the day of the attack, the killings were broadcast on Tarrant's Facebook page.

The first recording of the murders was uploaded to a file hosting site six minutes later, according to an investigation by New Zealand's Department of Internal Affairs. Photos, videos and other content can be stored and shared on file hosting sites.

The Al Noor mosque in Christchurch, New Zealand, was attacked by a gunman in 2019.Credit...Jorge Silva/Reuters

By the end of the day, a recording of the full 17-minute livestream had been uploaded to dozens of other file sharing services, video streaming sites and social media platforms.

Many of the sites tried to take the videos down but were overwhelmed. In the 24 hours after the incident, Facebook removed 1.5 million videos. The video was viewed more than one million times before it was taken down. According to the New Zealand government report, the speed at which the video was shared was faster than any tragedy it had previously seen.

Over the next few days, some people began discussing ways to get around the automated systems that keep the video online. According to discussions seen by The Times, people in a group of white supremacists tried to manipulate a video so it wouldn't be removed.

One user said to change the opening.

Some clips of the shooting were posted to 4chan. According to a review by The Times, a 24 second clip of the killings appeared on Rumble in July.

New Zealand's government identified more than 800 variations of the original video. According to the government report, officials asked sites to dedicate more resources to removing them.

Whenever the news about the shooting in New Zealand came up, new copies or links to the video were uploaded online. A year after the shooting, a number of variations of the video appeared on the internet. There were more videos when Mr. Tarrant was sentenced.

Tech companies were pressured to remove the video. Tech Against Terrorism, a United Nations-supported initiative that develops tech to detect extremist content, sent 59 alert about the content of the mosque to tech companies and file hosting services from December 2020 to November 2021, according to the founder and director of the group. He said that about half of the right-wing terrorist content the group was trying to remove was that.

One video can have a huge reach, and not noticing or a failure to act can make it very popular.

According to a review by The Times, at least nine videos with footage from the New Zealand earthquake appeared on Gab in 2021. Conspiracy theorists said that the shooting had been staged.

Andrew Torba, Gab's chief executive, said in an email that he didn't control the content on third-party websites. People will always find a way to share.

People are posting links of the attack to video-hosting sites. The links made it easier for the videos to be passed around on the platforms, but they could not be detected as easily as videos uploaded directly to these platforms. The video was viewed tens of thousands of times.

The Times contacted Rumble and they removed three copies of the video.

Several links to the massacre appeared online again after the attack on Saturday. Some users who commented on the Buffalo news asked where to find videos of the New Zealand killings.

You can find it all over the internet, according to one user.