Whenever I watch something on Netflix in browser the screen goes blank

I'll start a movie or tv episode and for 20 seconds or so the screen will go blank. I can still hear the audio, just the screen is out; and after around 20 seconds the screen comes back and I can watch it.

Why does it do this? I'm using firefox, but it does this with every browser. Screen doesn't go blank if i'm watching youtube or twitch.

Anyone got any idea? I have the latest drivers for video card and monitor