A lot of videos and movies you can download use codecs that do not come included with most computers. This can be very annoying, especially for people who do not know what a codec is or where to get one. Cole2k Media has a solution for this annoying problem. They have a downloadable codec pack with most common codecs that are used, but not included with Windows.
To get the codec pack, go to Cole2k's website and download one of the codec packs on the top left. If you do not know much about what you want or need, just get the standard pack and leave all the options default.