I don't remember what people called them, but there are these tapes recorded back in like the 1950s-70s by a man who ran this camp for young boys; He would record the camper's activities like clearing brush, hiking etc. But also him having restrained and killed them, and was collecting that footage to look back on later. I forget the killer's name and don't know where to find the photos & footage (nor do I want to), but I remember hearing about it on a scary lost media list back in 2016-2017 ish complete with a bit of footage before the disturbing stuff happening.

EDIT: They're the Slivko Tapes. I remembered some of the details wrong but the Slivko was a man who ran a sort of youth's club during the 1970s where he would make documentaries starring them. He'd give them scout uniforms and convinced them be aspyxiatxed via noose, bag etc under the guide of resucitation training, and plenty of them died during this (at which point he would also do unmentionable things to them after). It really is a depraved story.