This video is one of the most recognized demonstrations of granular synthesis—a technique that slices audio into tiny grains and reshapes them in real time. The synthesizer you see here doesn’t actually exist as a hardware instrument; it’s a visual mock-up powered by a computer, framed with keyboards, wires, and screens to illustrate how the process works. By moving the window across a sample, different parts of the sound are scanned, producing evolving tones and textures. Modulating the process

Granular synthesis: a beginner’s guide – Native Instruments Blog

Granular Synthesis: Here's Everything you Need to Know