AAMC has a website with information on VITA. There's also a practice VITA that you can do that's basically the same thing with the same format and very similar questions.
I actually
just took VITA. I looked over the FAQ's on the website, came up with some generic ideas like why I want to be a physician or a time I was challenged etc. Right before I took the real thing, I re-did the practice VITA because it gave me an opportunity to warm up and get used to looking up at the webcam.
I did wear a suit. I wore what I would have to a real interview.. top half at least, I wore leggings instead of dress pants