Why does my phone blink when attempting to play a video

[AC Question]

I try to watch a video, but every once in a while, the screen goes black and when it turns back on, it's a new background, and it'll keep going to black and I won't be able to stop it unless I repeatedly press the power button or restart the phone. I'll still have to change my background because it completely got rid of it. I'm using a ZTE but I don't know what version.