When I played movies on my desktop system, I had no problems as everything fit the screen perfectly. Now when I try to play the same movies on my laptop, the image does not stretch to fit the screen in some movies. I see two large black bars on both sides. Most of the movies stretch perfectly, but some movies show black bars. When I try to change the resolution myself such as 16:9, the picture fills the screen. The problem is it doesn't look normal this way - looks too stretched.
The native resolution of your laptop is probably not the same aspect ratio of the video you're playing.
You either change your resolution to match that of the video, which will cause the video to lose it's clarity, or you play the video at the native resolution of your screen which will give you black bars.
There's nothing else you can do really.