The trio, now aged 15 and 16, were detained for a combined total of 37 years on Friday for murdering 26-year-old Peter Cairns on June 11 last year as he and a friend tried out a moped on Silkin Way.
Mr Cairns was stabbed in the chest when and his friend were confronted by a group of armed teenagers after the boys were told to keep moving.
West Mercia Police has now released CCTV footage of the teenagers, who were then aged 14 and 15, before and after the attack.
The clips show the three joining a gang who were meeting a group of teenagers for a pre-arranged fight between two rival gangs in the Woodside area of the town.
During the trial at Stafford Crown Court, the jury heard how they were part of the TF7 gang who had collected weapons to confront members of the rival TF3 gang.
All three teenagers guilty of murdering Mr Cairns - who cannot be named for legal reasons - had weapons with them; a knife, a blunt Samurai sword, a wheel-brace and a hammer.
Two were then seen after the attack, running from the scene before they were caught on film laughing and mimicking their actions as their victim lay dying.
One of the boys, who struck the blow that killed Mr Cairns, admitted murder, while the other two were found guilty at the end of a trial.
The 16-year-old who stabbed Peter Cairns with a kitchen knife and admitted murder was sentenced to 11 years detention, while the other 16-year-old who was convicted of murder and used a blunt samurai sword was detained for 13 years.
The 15-year-old, who was also found guilty by the jury, was detained for 13 years.