In my garden, I've only seen them display to one another, but elsewhere they may get a little over-enthusiastic. Frith and Cooper report:
We occasionally observed a female-plumaged, presumed male, Victoria's Riflebird perform the Circular wings display to a passing bird of another species including a Wompoo Pigeon Ptilinopus magnificus, Pale Yellow Robin Tregellasia capito and Macleay's Honeyeater Xanthotis macleayana. Such a riflebird, perched on a bird feeder in WTC's garden, once directed this display to a Musky Rat-kangaroo Hypsiprymnodon moschatus beneath it and once to a moth as it flew slowly past, the bird turning to continue presenting its display to the passing insect.
Frith, CB & Cooper, WT. (1998). Courtship display and mating of Victoria's Riflebird Ptiloris victoriae with notes on the courtship displays of congeneric species. Emu 96: 102 - 113.