Go to Limewir>tools>options>saving>save folder to check where your downloads are going. Go to that folder, find the file and double click the file and it should open in your default player. If not right click and chose another player. VLC player is good for awkward video files and might be your answer
http://www.videolan.org/vlc/
I'm not sure if I understood the question correctly but let us know if you need more help