This is an old timers technique used by poor mans photography to create shadow less studio works before strobe lights were available. A film camera would be set on a tripod and the photographer would use a single tungsten light. Lights were turned off in the studio, camera shutter opened and the light pointed at the subject would be waved in an ark resulting in a very subdue soft shadow. In the early days exposures were a bit of trial and error.
I revisited this technique in the late 80s using a flash strobe with a bit of a twist. In almost any environment where studio lights where difficult to place or required too many lights a single flash can exceed your expectations. The only real limitation is a need for a dark space without light.