An interior rearview mirror assembly for a vehicle includes a mirror head having a mirror reflective element, and a video display device behind the mirror reflective element and viewable through the mirror reflective element when activated. The video display device includes a display screen that occupies at least 75 percent of a reflective region of the mirror reflective element. The video display device includes a backlighting array of light emitting diodes for backlighting the display screen, and the backlighting array of light emitting diodes includes a plurality of zones of light emitting diodes, with each zone having at least two light emitting diodes. The zones of light emitting diodes are independently controlled based on the video images being displayed by the video display device.