The reason Alpine doesn't state that they have a dedicated video input is because it is against the law, or so they say it is, and don't want to be put in a state of liability.
Here is how you would make it accept video, I've never done it though so don't make me liable =)
On the main cord of the cva brain (from monitor to brain) you have one end that has a 6 pin plug. There is only one green wire, that is your video input. Now take a RCA cable and cut the end off. Strip back the wires (you should have a single wire in the middle and an outer shield one) take the center on and take it to the gen wire on the cva harness. The outer wire from the RCA, that that to ground. Once these wires are connected, plug your video source (vcr, dvd, playstation...) hit the navigation button and you got video input.