I would think so.
Although I haven't done 4, my setup at work has two. You can set up two as "mirrors"... both displaying the same thing, and the other option is "Span", where the physical monitors appear as one large desktop. You mouse moves from left to right across both monitors. You can drag anything from one window to the other.
If you can hook up 4 monitors, I would think OSX will allow you to arrange them anyway you want. Although mine is left and right, I can set them to top and bottom as well.
So arranging 4 in a square, playing a video and having it fill the screen I think would be easy.
Just make sure your video is of super quality... making it that large will show all of it's imperfections.