Just had this happen with my dad's laptop. He was trying to watch a video on Facebook and while the audio played, the screen was almost as green as the ones they use in movies nowadays. Now, I'm no techie, but I went through the usual procedure of checking to make sure Flash was up to date and that Flashblock wasn't behind it. Yes and no on both of those. Then I checked YouTube to see whether it wasn't anything more than a Facebook problem and yup, videos on there wouldn't work right either, even after a good ole CTRL+F5. After that, I went for the tried and true method of diagnosing any computer related problem: I googled it.
having the fix.
Pictures via thewinterarcher.