What is "Active down-programmer"?
It just means that the power supply regulator output has a push-pull stage, like an opamp would, but stronger.
Normal voltage regulators only implement a push stage.
If you have pushbutton to set regulator feedback so that the output would jump from 5V to 10V, the push stage would quickly react and step the voltage from 5V to 10V as fast as it can.
But as a normal regulator does not have a pull stage, using the pushbutton to change output voltage from 10V to 5V would just cause the voltage to slowly go down as the load consumes current from the output capacitor, before the voltage settles at 5V level.
So a regulator with active pull stage, it would work like an op-amp, and quicky set the output voltage from 10V to 5V, discharging the output capacitor rapidly, regardless of load.