> I don't know if there really is a feasible solution - maybe a delayed-broadcast setup where a human moderator reviews each feed/view? Also maybe automatically have a human attach and watch feeds that are spontaneously getting popular without a clear reason, etc.
I think those are very good ideas for mitigating this kind of problem.
Facebook (and other internet companies) have basically built sharing platforms with no breaks, and that opens them up to exploitation by people like this mass shooter. I think the only effective solutions will involve retrofitting breaks and proactively inserting human moderators into the loop. There's literally no good reason that something should be able to go viral globally within hours of creation, not even disconnected natural disaster reports.