need alittle help

i downloaded a video file in avi and it will not play on media player and it will not let me burn it to a dvd it will only play the audio. what am i doing wrong?

 

plodr's idea is a good one, but if you aren't fairly knowledgeable in the use of codecs and multimedia in general, there's a good chance that GSpot's info will be useless to you (I love GSpot and use it regularly, but I wrangle a lot of video files). I think if you grab yourself a good codec pack and install it, you should be able to watch just about any clip you encounter. Here's a few packs:
KLite Mega Pack http://www.majorgeeks.com/K-Lite_Mega_Codec_Pack_d5230.html (my personal favorite; includes Media Player Classic and the Codec Tweak Tool for fixing/removing broken codecs)
Vista Codec Pack http://www.majorgeeks.com/Vista_Codec_Package_d5326.html (works with Win2000 & WinXP too)
Storm Codec Pack http://www.majorgeeks.com/Storm_Codec_d5491.html (also includes Media Player Classic)

(if you do want to check out GSpot, you can just launch it and drag-n-drop the video file into the top left space in the GSpot window and it will report everything you wanted to know about the file and will tell you if the codecs required to properly play the clip are installed)