How do I actually watch something that i downloaded from Utorrent?

Okay, so I downloaded a movie via Utorrent. It's 100% complete but when I open it, trying to use Windows Media Player, all I get is the audio. Could it be that I downloaded a file containing just audio or is it more likely that WMP just does not recognize the format? Please help with a detailed answer if possible, although I'm open to any kind of answer.