I was at Hong Kong, and Germany recently (both are prime 3G markets) and I have yet to see anyone using their 3G handset making video calls.
People are not doing it out of one reason – Privacy. Calling someone, at the core is a very private activity, and video call removes that privacy. Making video call (especially in public places) means you have to talk pretty loud and the people around you will also hear very clearly view of who you’re talking to and what the conversation is about. Unless you are a street performer, video call over 3G network will never be a good experince.