If you are from the usa then you want ntsc european uses pal. Try opening the file by right clicking it and choosing OPEN WITH - try the different players in your choice. There is also the possibility it wont open because it isnt a media file at all. For example windows media or showtime may not work and open the file protecting your computer from erratic behavior. Unfortunately there are some people who will try and send out a virus or worm. Your antivirus program , windows media player , showtime etc wont just start playing it if it doesnt recognize it as mpg avi mpeg etc. It may ask you first with a warning or the player will just shut down. Try staying away from videos under 40mb.