Switching between full screen and zoomed mode in videos 9

When you are watching a video that you have either loaded on to your device or streamed from the web (as opposed to a video taken with the camcorder), have you ever noticed that your video may be zoomed in so part of the top or sides get chopped off? Or maybe you are watching a video and you see black bars on the top or sides of the video? You can actually swap between these zoomed in and out modes in your video by first tapping on the screen to bring up the video controls (if not already shown), and then tapping the  icon to zoom in (to get rid of the black bars on around the video) or the  icon to zoom out (to see the full video).