But on Wednesday, the video that was auto-playing in everyone’s feed showed the murder of two people. It’s impossible to tell how many people saw the video (though Facebook’s version of the video was shared 500 times before it was taken down), but user reports suggest that thousands and thousands of people witnessed—without being warned ahead of time or knowing what they were getting themselves into—a brief, vivid, and unmistakable snuff film.

Forcing thousands of people to view two deaths without warning or preparation causes real harm. For almost all viewers, of course, watching the video does not approach the anguish felt by the victims’s friends, families, or coworkers. But that the auto-playing incident was not the worst horror in a morning full of them doesn’t lessen the need to talk about it, to figure out what happened, and to prevent it from happening again.

When I asked Twitter for comment, it referred me to its media policies, specifically this section: “Media that is marked as containing sensitive content will have a warning message that a viewer must click through before viewing the media.” There is a brief period of time, though, between when a video is uploaded and when it’s tagged as sensitive, and many people saw the video during that gap today. I also asked Facebook for comment but haven’t heard back yet.

Twitter and Facebook were not the only venues showing video of the murder on Wednesday morning. CNN was showing the TV station’s version of the video once an hour. But that kind of viewing is different, I think, than the auto-playing mayhem that descended on Twitter this morning, because there was a warning before it. Except for someone changing the channel directly into the brief footage, a viewer would know what they were about to see and choose whether to watch it or not. I think, too, that the TV station’s version of the video was profoundly different than the murderer’s version, precisely because it was not filmed by the murderer.

There is some question as to whether media outlets should be showing these videos at all. In 2012, the sociologist Zeynep Tufekci wrote for The Atlantic about research suggesting that mass shootings, like teen suicides, are contagious: that by describing the specific method and setting of the killings, law enforcement and the media can prompt more of them. But while I don’t know that CNN is making the right choice to air the video, I do trust that they are thinking about it—that they are considering the airing of such a video as a meaningful act, one with possible benefits and consequences. I trust that they are thinking about it, in other words, editorially.

When Twitter debuted video auto-play earlier in June of this year, meanwhile, they talked about it as a technical improvement. “Rich media creatives will now auto-play in timelines and across Twitter,” said a company blog post, describing it as a “consistent, seamless and friction-free” change which would lead to “a more streamlined consumption experience.”