all videos etc. don't show up?

i have a macbook and everything was working fine until yesterday when i suddenly could not see any youtube videos, or any ads or things like that. instead there is the quicktime icon with a question mark, or just the icon.
i've had this computer for almost 6 months, and i didnt have a problem until yesterday morning, can anyone tell me what's wrong with it? and how to fix it?
thanks in advance <3

what browser are you using?

this is an xp problem, ive had it before.

i think i just ran an update, or reinstalled and it vanished...

i was having problems viewing yahoo sports movies.... i think they are flash based, and i had done everything i could with MM flash

i got it fixed.

well i took it to the Apple store yesterday, and it does indeed have something to do with me running an update shortly before it happened... they fixed it for me though...