O.K. what I meant to say was stretch across 2 Monitors but Yes I understand the file size would be a bit too big. On Windows 8 there is no setting 'Stretch video and static wallpapers over multiple monitors'.
So, I will go on as is. Thanks for the info.
Sure there is, you just have to poke around a bit. In Win 8, select a dream. Click on the Adjust button and additional settings will be available including stretch.

P.S. In fact, it works quite well and looks great. My monitors are 1680x1050 and 1440x900.
