If YouTube Videos are playing sound but not playing video, and instead you see a Green Screen, the following simple solution is for you. I have personally experienced the Green Screen video playback issue (videos showing green and wont display) shortly after updating Adobe Flash Player. As it turns out, correcting a simple Abobe Flash Player setting resolved the problem.
How to fix Green YouTube Videos:
If YouTube Videos Look like this...
- Right Click within the Green Video window, and select Settings
- Uncheck the Enable hardware acceleration Box and then click Close
- Refresh the page (F5) and try to play the video again.
If all went well, you should now be back to watching your YouTube Videos.