How To: Use ADSR Envelopes in FL Studio

The famous ADSR Envelope (Attack, Decay, Sustain and Release)... It's seen in almost every virtual instrument or software synthesizer from Albino to Halion to SampleTank to Z3ta but do you know what it does?
In this tutorial NFX tries to explain how an ADSR envelope helps shape a sound. To demonstrate he uses the FL Studio sampler channel but the way ADSR works is the same in just about every instance.