I have a couple errr....videos that i downloaded long ago that simply won't play in media player, divx or anything else. Dont remember what version of media player they played with but is there a program that will just play pretty much anything you throw at it?
Video LAN plas a lot of formats and might work. If you right click on the file in explorer and go to properties, it usually displays the video and audio codecs. If not, get GSpot to see what codec it is.