How a Transmission Park Brake Works 

Yet another misleading caption; this video does not explain anything about the operation of a transmission brake.

19 mar 2019 12:17 pm edt: i'm confuse i thought drum-brake is for parking-brake,not automatic-transmission->park/parking-pawl thanks

This is not a transmission brake. This is a regular wheel based parking brake. A transmission _brake_ (not to be confused with the park _gear_ ) is a brake connected to the drivetrain. Often somewhere on the driveshaft. When applied, it prevents (or at least retards) the ability for the driveshaft to rotate.

So trans brake = parking brake

Why is this narrated by Jeremy Clarkson?