Most LED bulbs run on Alternating Current (AC), which means they’re turning on and off 100 to 120 times per second (120 for US which operates at 60 Hertz, 100 for most of the rest of world).

Video cameras operate by stringing together lots of still images, called frames. The rate at which it takes these images is called the frame rate, typically expressed in frames per second (FPS).

Flicker happens when the camera’s frame rate and the LED frequency don’t align, causing some frames to be taken while the LED is on and emitting light, and some frames to be taken when the light is off.

LED flicker can thus be avoided by aligning the camera’s frame rate with the frequency of the LED.

Because LEDs on Direct Current (DC) receive a continuous, constant current they’re not switching on and off and thus don’t suffer from this problem.