Video display problem with Galaxy S7

[KikiHalbert]

Some of my apps on my phone have videos that they can play. But when I try to play them, I hear the audio, but the screen is black with the exception of one line of colour at the edges of the screen, or at the top of the screen. Help please?

 

[B. Diddy]

Welcome to Android Central! Which apps, and what kind of video files are they? Can you use the stock Video app on the phone to play these videos as well, or can you only use those specific apps?