If you upgraded Adobe Flash Player on Ubuntu recently, you may got Youtube flash videos blue tint problem. This is an Adobe’s bug on Linux machine with nvidia graphic card.
For now, you can fix this problem by installing patched libvdpau or by disable hardware acceleration.
Method 1. Installing patched libvdpau by adding this ppa:tikhonov/misc. Use the graphical method adding this ppa or execute following commands in terminal (Ctrl+Alt+T to launch terminal):
sudo add-apt-repository ppa:tikhonov/misc sudo apt-get update sudo apt-get install libvdpau1
Method 2. Disable hardware acceleration.
Open any video from Youtube and switch to Full Screen Mode, right-click and select Settings…. Try several times to bring the setting window up. Or log out and back in using Unity 2D mode then try again.