Bias lighting has many applications and all revolve around creating a specific perception of your image by controlling your perception of color or how much the iris in your eye moves. This can be accomplished with standard lighting to a degree but all light has a color to it and for video D65 is preferred.
http://www.cinemaquestinc.com/ideal_lume.htm
http://www.cinemaquestinc.com/ideal_lume.htm