First look at the specs for your card at your manufacturer site. See how many monitors it support. Minimum would be 2 I think but 3 is very common for mid level cards and that was mid level. You really just need an adapter for the ports you have. Your card may have come with a dvi to vga. You may only need a mini or full display port to vga ACTIVE adapter. Assuming it has display ports, if you have one that has two DVI ports and no Display Ports then you need 2 dvi to vga.
I would add that you pretty much said the same thing yourself.
Are you asking how to set up eyefinity?
Are you asking how to even get multiple videos to play at the same time? Like VLC will play a video in a window and you click another video it replaces the one playing. If you changes settings however you can play multiple windows at one time.
Sorry just not exactly sure what you are asking and trying to cover the bases.