Not entirely sure of the Puma rotor brake, but on the S76 type, it's basically a hydraulic system, similar to a caliper and brake disc on a car, whereby the disc is a part of the tail rotor drive shaft. Now they do generate a lot of heat, hence the reason why there is a limited time between applications.
One of the issues in flight, if it starts to tighten, is the massive amounts of heat generated and /or failure of the drive shaft itself.
Some people (those without mechanical sympathy for the machines they fly) can be seen applying the brake quite harshly, and as an ex engineer, it always makes me wonder why people continue to do this.
The movement of the blades backwards is probably just from the blade dampers (again, a hydraulic piston and cylinder) being compressed with the forward inertia of the blades, and once the blades come to a standstill, the hydraulic pressure in the dampers moves the blaeds backwards. Nothing more than that and nothing to do with winding the transmission up.
People could be a bit more gentle with the brake tho, IMHO.