In the expletive-laden video, Stewart refers to apprentice painter and decorator Kayden repeatedly, including by the initials KM – he says that people know “KM is dead”.
He says: “Everyone knows my scheme is violent, big plan for future ahead. I just love being a bloody ned.”
He also appears to threaten further acts of violence “when I get out”.
A court heard that Stewart and the 15-year-old – while acting with Turley – chased Kayden, from East Kilbride, and repeatedly stabbed him with a lock knife after he fell to the ground.
Stewart brandished his baton and was heard to shout “Murray Boys”. He then told a witness at the scene that his victim “deserved it.”
After running from the scene, Turley stuck the knife into the grass and was overheard boasting that he “just done him.”
Turley also shouted “One-nil.”
CCTV showed the trio running down a road near the beach – stopping momentarily to embrace each other.