If you're in Jacksonville, Florida, you have to know where the local DCTN POP is and buy the T1 to that point to connect to the network. The closest POP to London is Norfolk. A T1 across the ocean is very expensive. It's hard to resist the temptation of comparing DCTN to VIXS, but actually, it isn't fair. Most DCTN sites use nearly an entire T1.
Video teleconferencing is near full motion.
Obviously, the lower the bandwidth, the jerkier the motion will appear. It's not the TV standard, but it's usable. I watched a VTC conference at 64 kbps, and when I say usable, it's just that, not much more. These are the intangibles that lose so much in the translation. It's the difference between talking across a table and trying to do the same thing over the telephone.