In the main video we are switching the filament after a nozzle change using the Prusa MMU (Multi Material Unit). In short, the MMU pulls the old filament out -> selects a new filament -> then loads the new filament in. (The Swapper3D cuts the filament before the MMU pulls the old filament out to prevent possible strings and jamming.) The Swapper3D can also use these filament switchers: Mosaic Palette (any version), CoPrint, ERCF (enraged rabbit carrot feeder), Ryper MMU, 3D Chameleon, and any other similarly designed filament changer.