I thought so too, but at 20:55 you can see the rider stop pedalling while still rolling. It seems to contain a freewheel mechanism: https://youtu.be/Yqgn-qlg1X0?t=1255

It's a "coaster" hub, very common on cheap single-speed bikes. It allows you to coast without pedalling, and by applying backwards pedal pressure it activates a drum brake.

Definitely not enough braking force for this bike weight though.