Which codecs?
 

I tried to play a file, and it said I needed codecs. How do I find out which codecs I need?

Please don't double-post!!!

Please in future search your topic BEFORE posting. Also look at the Stickys at the top of each section before posting. Your answer is sitting there already! Press the GO button below left & you'll see a sticky called Major problems for Downld/Upld Problems Sticky & all you need to do is click it & look for your topic. I'd suggest you get GSpot. There's a link for it in the post in question. Also a backup player with built-in codecs such as VLC will play almost everything so consider getting it also just in case for future viewing problems.