Of course K-lite codec pack is powerful tool for moview codec decode, but when you download movies from the internet, is very vital this fact that is your codec up to date? For example here I have download K-lite with version 4.90, so try to always check newest versions: http://www.video-codec-pack.com. Also you can download just video codec, for example popular of them are FFDShow, Xvid and Divx video codes, it is not codec packages, it is separate video codecs, so also hold you hand on pulse :)