anyone who even barely studies linguistics or deaf culture will tell you that a 3-D language like sign language.. A- since there is no written sign language (of any major use), you are actually forcing deaf people to use their non-native written english... it will never be as good. 2- Video chatting is using their native language, incorporates facial expression and they can fully express their thoughts and sentences. There are so many intricacies, you would be surprised.