Line Lock with Drum Brakes ?

Unless it's a bootleg rear doing a one-wheel-wonder burnout, the rear wheels are both spinning & driving the car forward, it ain't the brakes.
I’ll add to that, HOW is he doing his burnout? slooowly turning tires or like I do, smack the gas pedal hard, 1-4500 2-4500 3-4500 once smokeing good release lock and ease out under power. Let off gas stop back in first move forward under slight power to set spragg. Go to pre-stage line, no dicking around