Delay is inherent in digital video. If activate the camera on my smartphone and wave my hand in front of the lens, I can easily get the hand on the screen moving in the opposite direction from the object itself. That's only a fraction of a second, but it's not hard to believe that IFE equipment (and whatever else may between the camera and the screen) introduces more complexity and more delay. The delay might also vary depending on the demand on the processor(s) at any given time.