There is a known problem with very large files such as video files completing the last 1%. So chances are if there's anything missing at all it's the credits. Go to LW's Library window, select the incomplete folder, select that file & press launch. If you can play it to the end then it's fine. Cancel from download window & remove from incomplete folder. (ie: select incomplete folder, press Explore button & this will open the folder & you can move from there.

BTW the best program for previewing or launching videos thru LW is VLC - (click on link) _ (choose nearest mirror site)
See what it can do http://www.videolan.org/vlc/features.html