I make comedy skits on YouTube weekly.
Practical light(ing) is the light emitting objects that exist in a shot whether or not the practicals are used as motivational lighting for the talent. An example being a candle in the background, but the cinematographer/photographer chose to instead motivate the light from what the viewer assumes is the moon. Even though the talent is lit by the moon and not the candle, that candle is still a practical light. Practical lighting is used in the videos above as a term to motivate light through the use of practical lights in a scene.