The document discusses the importance of lighting in movie trailers for setting mood. It notes that trailers typically use brighter lighting for happy scenes and darker lighting for sad or intense scenes. It analyzes the lighting used in the trailers for the movies "Me and Earl and the Dying Girl" and "If I Stay" as examples that convey different emotions through lighting. The document concludes that using varying lighting, from bright to dark, can help make a trailer more authentic and impactful in portraying different moods.