Bitwig's modulators can be assigned to any MIDI CC parameter on an external hardware synth, effectively expanding its modulation capabilities beyond its built-in options. The tutorial uses the Arturia MiniFreak as a concrete example: the synth already has two onboard LFOs controlling oscillator wave and timbre, and Bitwig adds a third LFO targeting filter cutoff, something the hardware alone couldn't do.
Function generators, envelopes, step sequencers, and other modulation sources can be stacked and combined freely, letting you build custom modulation architectures around any hardware instrument directly inside Bitwig.