The proliferation of iPhone X videos in recent days has led to some concern about a flashing light on the front of the device -- but that is just the infrared dot projector being picked up by digital cameras and it is not visible to the naked eye.
Social media is alight not only with links to the videos, but concerns about the flashing light -- the color of which appears to be related to what camera is being used to capture the video. The "light" either flashes once in the case of an unlock, or multiple times when being used for Animoji mapping.
The effect is amplified in appearance with a dim background.
The most common source of the infrared strobe is the Dot Projector at the core of the TrueDepth system. The Proximity Sensor can also generate the effect as well.
All digital cameras are susceptible to infrared capture to some extent or other, depending on what device manufacturers have put in place to stop the effect. The response to different wavelengths of light in a charge-coupled device (CCD) in a digital camera varies from the human eye -- and an artifact visible to the human eye is generated in a video a result of the exposure.
Users without an iPhone X as an infrared source can duplicate the effect by starting a video capture, and pointing a TV remote control with an infrared emitter at the camera lens and hitting buttons. The resultant light in the video or image capture is the same effect in action.