DisplayFusion isn't currently able to force full screen video to span multiple monitors due to technical limitations. However, if you have a video card that support Surround or Eyefinity, you should be able to combine the group of monitors into one large display. Alternatively, you could use something like this to present three monitors to the system as one large one: http://www.matrox.com/graphics/en/products/gxm/th2go/digital_se/

Hope that helps!