CODECs list and alternate players for Movies (click on link) If VLC can't play a video file then I'd be extremely worried. It sounds like a system issue to me. VLC is a very trusty program & has in-built codecs. It it can't play a file type that it's supposed to play then I trash the file.

Are you trying to preview or launch the player thru LW? If yes, try opening the file directly with the video program. ie: select Open file from the menu & direct it to where the video file is.