Actually, I said that because none of my players so far have been able to play what I exported the right way. If I say full screen it wants to use one screen. If I try to stretch it, it still isn't quite right. Quicktime is the closest. VLC and Windows Media are lacking.
There must be a player capable of full screen across two monitors, but I either don't have one or I don't know that I have one.
Edit: VLC did better when I changed the settings but it still isn't perfect.