Is there any relation between a Exposure & Flicker
Video is refreshed at a certain rate, depending on the display device, between 24 to 60 FPS. Any time you shoot video a a faster shutter-speed you risk the camera taking shots will the between refreshes.

If you take a photo with a slower shutter-speed, say 1/20s, then the camera will capture an entire refresh cycle and the flicker will go away. Use shutter-priority (S or T mode, depending on your camera), Manual (M) or time-aperture (TAv) mode to control shutter-speed yourself.

PS: I realize your question is slightly ambiguous. I am assuming you are taking a photo of something that is playing a video. If you are shooting a video of a video, then your question is off-topic here.