The document discusses how different genres of films use music, lighting, sound, and cinematography in their opening sequences to set the tone and put viewers in the appropriate mindset. For example, a thriller opening may use slow, string music to create a sad and chilling atmosphere that hints at impending danger, while a comedy could use a more upbeat song with lyrics related to the film to get viewers laughing. The genre shown early on is important to prepare the audience for the type of experience they will have watching the different types of films.