First of all, did you check the file with Bitzi before download? Heaps of .mov files are just spam & porn
How to use Bitzi

mov files

You could try VLC player, it's free & plays most things.
VLC media player - Overview

To change the default player: Go to LW's library, highlight the file & click Explore. Now your saved folder will open. Right click on the file > open with > choose program. Select the player you want from the list. Tick the box to 'always use the selected program to open files of this type' > ok.