You will have to use a codec to play a video using Windows Media Player (or Prism) and to convert from such a file or to convert to it as well. If you have an existing file try playing it with Windows Media Player (not the excellent Windows Media Player Classic, as it has codecs built in). If the video plays then you already have the needed codec installed and Prism can convert it.
If the video still does not play, you will need to locate a codec for it. There are a number of good utility programs that can tell you the codec for a given video. Listed below are two such programs:
These applications will also provide download links for the codec in question.Locating the Codec
There are a large range of sites you can download a codec from. Listed below are a few: