 the play of shadows as the bulb moves is far  too accurate. But if the bulb is actually lit, then there must be a  power supply somewhere. If the viewer watches closely while Anton is  swinging the bulb about, a wire can be seen coming out of his  sleeve, to be obscured behind the bulb. It should be noted that  there is never a single, continuous shot showing the entire  circumference of the bulb. This is most likely because the wire  front Antons sleeve runs along the "back" of the bulb to supply the  necessary power.