* As I understand it, the phones use a webcam-type second camera for this video and not the photo camera the phones might have.

I wish it was that way. Right now they only offer 3 phones that will be able to take advantage of this. 2 Samsungs and an LG. The Samsung a717 and 727. The LGCU500. The 717 and the CU500 both have cameras that rotate and the 717 I'm guessing has to be turned around to transmit your own mug if thats your wish. That said these all use the main camera as it is the only camera. AT&T has decided to take different versions of devices that lack a second camera for some reason. Perfect example is the HTC Tytan. AT&T went 8525 which is basically the same phone sans the second camera for video calls.
AT&T has an odd idea of what reasonable price points are. Just look at how high the data prices are. They are just now coming to grips with decent sms pricing and they still have a ways to go.