“Mainstream platforms are putting resources into moderation, but it’s a bit like closing the barn door after the horses have gotten out" The problem isn’t just new content; once a video is streamed, it spreads, often to sites that have no interest in policing what they host or that lack the resources to moderate. “It will take awhile to undo the years of allowing these materials to proliferate and have a foothold on all of these platforms.”And moderators at any one company must reckon with the fact that, ultimately, social-media platforms form a collective ecosystem, ranging from the mainstream to the fringe—Part of the challenge of moderation is that users may act differently in different spaces, appearing anodyne in one and toxic in another. "