No part of the LEDs or the neon glow tube move when you give the Bronx cheer. Instead, your whole body is vibrating, including your eyes. But when your body is vibrating, your eyes are in a different position each time the bulb flashes. As the image of the bulb traces a path across your eyes, it looks like the bulb is moving and flickering. An incandescent bulb won't flicker when you give the Bronx cheer, because the bulb doesn't flash on and off.
Incandescent bulbs give a steady glow.
Plug a commercial neon night-light into an extension cord. Tape it firmly in place. Twirl the light around in a circle. Notice that you can see the light flashing. Since the light is moving, it's in a new position each time it flashes.