Videos praising the two US students who went on a rampage and killed 13 people in Colorado nine years ago have been removed from YouTube.
The videos came from all over the world and glorified the Columbine High School killers - Eric Harris and Dylan Klebold.
Amongst them was one the BBC team investigating the phenomenon showed YouTube.
It was made by a 17-year-old video maker called Levi, from the North of England, who was one of the few who would speak to the BBC.
He said: "I made the video to raise awareness and I in no way shape or form meant it to look like that [a glorification of the killers]".
"I wanted to show different sides of them, the personal sides of them, rather than glorifying it. I wanted to let people see behind the killers and see they were real people."
The pair shot and killed 12 pupils, and a teacher, and wounded 23 others before shooting themselves.
The clips have been taken down.
YouTube has defended itself saying that it is not possible to moderate all of the thousands of clips that are posted to the website.
Peter Barron, Head of Communication for Google UK, owners of the site told the Beeb: "We do not tolerate videos that glorify school shootings and have removed the videos that fall into that category".