Movie Aspect Ratios
I assume you're referring to movies that have been released on Blu-ray and DVD with a 1.78:1 (16:9) aspect ratio instead of what they used in commercial theaters, probably 1.85:1 or 2.35:1. Studios sometimes crop their movies this way for home viewing because people complain so much about letterbox bars above and below the movie when displayed in its original aspect ratio on a 16:9 HDTV. However, I much prefer to see the entire image as intended by the moviemakers, so I also hope the trend does not continue.
One interesting counter-example is Avatar, which was shot in 16:9 but cropped to 2.35:1 for somebut not Imaxtheatrical presentations as depicted above. The Blu-ray is 16:9, which is the aspect ratio James Cameron intended for that movie. Then there's The Dark Knight, which has some scenes shot at 16:9 and others shot at 2.35:1. The aspect ratio changes during the movie, but I don't often consciously noticestrange, but true.
If you have an A/V question, please send it to firstname.lastname@example.org.