Mr Justice Newman said Neil Sayers and Graham Wallis "fuelled their fantasies" from the videos which left them incapable of knowing when to stop.
Sayers, 19, was yesterday sentenced to life imprisonment for the murder of 17-year-old Russell Crookes, and Wallis was ordered to be detained at Her Majesty's pleasure.
The judge at Maidstone Crown Court said the pair had discussed, planned and prepared the barbaric murder of their supposed friend last May.
Tthey burnt his body on a funeral pyre and dumped his charred remains in a shallow grave, breaking off for orange juice and biscuits.
"As he was repeatedly stabbed to death by the two of you, he pleaded to you while you were stabbing him ... your silent response was to ensure he died by further stabbing him," said the judge. He believed horror films and internal rivalries in The Brotherhood, a survival group the three had formed, were the most likely trigger for the murder. They were also obsessed with the Army and survival techniques.
"You created a world of your own because you felt you did not adequately fit into the one around you," he said. "From the creation of this clique you achieved a strength and purpose which you felt was not otherwise available to you.
"Anything which threatened, or was perceived to threaten, was hated by you - French, Americans, gays and so forth.
"They [the videos] carried a potency that could not be readily predicted and served to desensitise you and remove from you the enormity of killing a person by stabbing them."
Sayers, the son of a retired army warrant officer, was found guilty of murder last month. Wallis, a bank manager's son admitted the charge and named Sayers as his partner in the killing in the woods near their rooms at Hadlow Horticultural College, at Tonbridge in Kent. Neither have shown signs of remorse.
During the nine-day trial Darren Rifat, a student at their college, said the three boys were obsessed with the SAS, and when they watched war videos they would replay the goriest bits, laughing when people were shot and fell down.
Before the murder, the three were inseparable but Wallis and Sayers made a pact to kill Russell because he was a bully and was annoying them.
Outside court, Russell's father, Malcolm, said his family had also received a life sentence. But he said he believed the videos the boys had watched - including Scream and The Evil Dead - were "not abnormal" for 17-year- olds. Detective Chief Inspector Dave Stevens, who led the investigation, said: "They were not banned videos ... but it was the context in which they were watched, what they did to the minds of the defendants."Reuse content