An 18-year-old and a 17-year-old were arrested and taken into custody at a south London police station in the early hours of Thursday morning.
The victim, named as 23-year-old Shane Jerome, was fatally knifed opposite Brixton Tube at 8.20pm on Wednesday, July 21.
Mr Jerome, who lived in Thornton Heath, was said by locals to have been riding a quad bike for a music video outside a chicken restaurant in Brixton market.
Forensics teams have been examining a damaged rental bike and quad bike in the wake of the killing.
Mr Jerome died 45 minutes after being attacked, with paramedics battling to save his life. Trauma doctors from London’s air ambulance were also scrambled to the scene.
Detective Chief Inspector Kate Blackburn, leading the Metropolitan Police’s investigation, said: “It has been just over a week since Shane tragically lost his life.
“These arrests mark significant progress with our investigation and I hope it brings some reassurance to both Shane’s family and the wider community that my team are working around the clock to bring justice for his murder.
“I continue to urge anyone who was in the area and who may have seen anything, or have footage on their phone or dash cam, to please contact us.”
A 19-year-old man was also arrested on suspicion of GBH but has since been released with no further action.
An onlooker told the BBC the video had involved a number of high-end cars, including a Lamborghini, a Ferrari, a black Range Rover and two quad bikes.
A witness said: “There was a rap video being shot in the market with men on balaclavas next to Lamborghinis and quad bikes. A bit later all hell broke loose. There were fists flying a convoy of vehicles on the move and a guy left laying bleeding on the ground.”
Mr Jerome worked as a part-time stunt rider and was also a scaffolder Croydon where he was brought up.
Anyone with any information can call police via 101 quoting reference Cad 7056/21Jul. To remain anonymous contact Crimestoppers on 0800 555 111.