There is a Flash video problem that is peculiar to Linux users using certain Nvidia graphics cards, and that is YouTube and other Flash videos render everything with a blue tint, so that people look like Smurfs, or like the Na'vi in Avatar. Figure 1 shows what it does to Limor Fried, founder of Adafruit Industries.
This is due to a bug in Flash 11.2 that interacts incorrectly with the VDPAU (Video Decode and Presentation API for Unix) library.
libvdpau moves some video decoding functions to the GPU, which should improve performance and reduce the load on your system's CPU.
libvdpau is used by GeForce 8 and newer Nvidia GPUs. The easy fix is to turn off hardware acceleration for Flash videos. To do this, simply right-click on the video and you'll see this:
Un-check "Enable hardware acceleration", re-start Flash, and your colors should be back to normal:
There is a good detailed discussion about this, and also the related problem of Flash videos always staying on top in an eerie, ghost-like way, on the Arch Linux forums. There are several other fixes to try if you're in the mood, like mucking with configuration files and patching
libvdpau. Or you could wait until the fixes percolate into your Linux distribution. Or just disable hardware acceleration. Or have a little fun with it, like give the Na'vi normal flesh tones and turn the humans blue.