After a few Google searches on this, it seems like this issue is cropping up for people with Nvidia cards…..

I upgraded Ubuntu to 9.10 and found that all of my video content was being displayed with many of the colours totally messed up – pink sky and green skins on people!

For some reason the Hue graphics setting was set to -1000. To fix it, I corrected the setting via the graphics preferences in the Totem media player and everything looked fine afterwards.