First, update your DirectX.
Second, update your VGA driver. (Can give you a link if you tell us what VGA have you got.)
Third, install a codec pack with player. My favourite is CCCP pack.
(On the website there is a CCCP Insurgent. It detects the conflicts. Try running it first before installing the codec pack. Something may have gone wrong between the codecs.)
(In browsers, you use Flash Player. It comes with codec support AND the video on the other side is converted in a format which Flash Player can play without a problem.)