If you're a getting a green screen (where you can only hear the audio and not watch the video) while trying to watch a video in YouTube or Facebook follow the following instruction to resolve your problem:
1. On the Flash Video 'right click'
2. Click on Settings and DISABLE this --> 'Enable hardware acceleration.'
1. On the Flash Video 'right click'
2. Click on Settings and DISABLE this --> 'Enable hardware acceleration.'
Click image to enlarge