The Watchout system is produced by Dataton (http://dataton.com), a swedish software development company. It allows simutaneous projection of video across multiple screens and does some feathering at the edges of the screen to make the video appear seamless. It is possible to composite both quictime movies and flat graphics (photoshop, PNG, JPEG, TIFF and others).
I have some info about our machines at:
Wathout Machine Specs
dimensions for our window:
Watchout Window Dimensions
some notes I took at a two day workshop about the software at:
Watchout Workshop Notes