The last big update Adobe did for Flash on Ubuntu resulted in a screwed up looking Youtube videos for many users. Those of us running nVidia video cards are the block of people reporting the "blue people".
There are a few ways to go about fixing this and we will walk you through the easy method #1 and the #2 method which is just as easy but using the terminal.
#1 - remove hardware acceleration on youtube videos
#2 - uninstall a package called "libvdpau1"
#3 - regress to a previous version of adobe flash which we arent going to cover.
So the first method is to right click anywhere in a Youtube video that you have playing and pull up a menu with the option to uncheck and disable "hardware acceleration". This may take a few times to do and if you still cant uncheck the box try logging out of your Ubuntu and log in using Unity 2D mode.
The second method is to uninstall "libvdpau1" with the terminal command of:
sudo apt-get remove libvdpau1
Either method works great. I will note that the second method also removes a couple other packages: mplayer and mencoder. Usually you dont need those, but some programs like devede will make use of them.
In case the second method doesnt help you and you want to go back, type this in the terminal:
sudo apt-get install libvdpau
and this will put you back the way your system was with the blue aluminum koolaid people :)