Hi there, i just got the game and am wondering something.

I bought it via digital download (not steam) but can't seem to find anything about where the extra content is (the wallpapers, music, videos etc), is it installed somewhere on my PC already?.

I did try searching the forums and goolge but couldn't find anything (perhaps my search skills are not good).

Any info would be much appreciated.

Go to "My Account" click The Witcher 2 and there you'll find them

My game isn't on there (just 4 free games), i got it via D2D.

In that case they're not going to be there because you bought it at D2D. Those free games come with registration; everyone who registers get those free games.