Is it good design to cover part of the video display with control buttons?

Long time ago video control buttons were being placed just below the display area so nothing was overlaying the image, then some strange fashion was introduced - moving these controls on video image so when you pause video to see image details or subtitles you cannot see them because they are being covered with big triangle in the center or control buttons on the bottom. I think this is very bad from UX point of view and am wondering why this behavior is so popular in players.