I have a really weird problem, when i watch a video on YouTube it is appearing like a negative, if, however, i search for the same video through Yahoo and watch it that way playing youtube through Yahoo it is normal. It happened after the update I did yesterday. Videos on my Mac are fine, just my Ubuntu PC, I am using 11.10.

I may be just a complete noob and have done something silly, but it really has me scratching my head

Oh yeah, and I am using Firefox