Pixel errors in movies?

I recently liked the fact that every movie I start the picture completely pixelated and blurred I watch my movies on the Xbox One S run the games Top but that with the films is very annoying, there are any ways to fix this?

How do you watch the movies?

Are they being streamed? If yes - artifacts by coding / encoding / bad line / Wlan.

Problem when playing a disc? No idea - ask for Xbox support.