Thanks to those at techguy.org, I found the solution. I turned off hardware acceleration. Here is the complete thread:

http://forums.techguy.org/all-other-software/981417-solved-cant-watch-youtube-videos.html

Here are the instructions to turn off hardware acceleration: http://www.deskshare.com/resources/articles/dmc_turnoffhardwareacceleration.aspx

It may be sufficient to only turn off the hardware acceleration in the Flash player.

See Flash videos won't play full screen

• http://www.youtube.com/swf_test.html (right-click the player: Settings)

Flash "Display settings" window:

• http://www.macromedia.com/support/documentation/en/flashplayer/help/help01.html

thank you!

Thank you. I was also having this issue and it got annoying. I didn't know hardware acceleration had anything to do with it. Once again, thanks!

Thanx. This did the trick

I tried turning off hardware acceleration. It does not work. Does anyone have any other suggestions?

Thanks in advance, Mike

Adobe has a 10.2.152.35 which was changed to address some Youtube + fullscreen issues which may fix this.

@cww:

Adobe has a 10.2.152.35 which was changed to address some Youtube + fullscreen issues which may fix this.

Where can you find that 10.2.152.35 version? I only see the 10.2.152.32 version offered on the Adobe test page.

• http://www.adobe.com/software/flash/about/

I'm on Linux, so can't test which version you get if you download the latest Windows player.

I cleared the firefox cache and deleted all but a few cookies as suggested by cor-el in the following thread.

https://support.mozilla.com/en-US/questions/789576?s=youtube+videos+won%27t+work&as=s

It solved the problem for me on two up-to-date systems.

Pay attention on the period that you clear the cache. It must be everything.

Cannot be hours or just today.

Solve blank / black screen problem while playing youtube videos in full screen mode by OriginalTips.com.

http://www.originaltips.com/youtube-black-screen-problem-on-fullscreen-solution-24