Well projection shot is the method usually used in the movies and the short films to avoid the costly on location shots. In this projection shot, basically subject will be made to stand infront of the large banner or screen which shows some locations like beach or any other location. Photo or video of the subject is taken by making the subject to stand infront of the screen. For viewers it may look like the subject is standing originally in that particular location. Thus when you plan to take movies or shortfilms at the very low budget, these kind of projection shots will help you save the money by capturing the shots in the studio by without taking the subject to the actual costly locations.
Even nowadays, photographers are smarter and even started using the videos in the projection shot. That is the subject is made to stand infront of the large projectors, Videos or Scenes will projected in the large projectors from the long distance. Now when you record video by focussing the subject, it will look like the subject is standing in the actual location. This method helps the movie producers and the directors to save lot of money.