I want to say once again that I think we have a responsibility to do our business in public, unless there are good reasons to be in private such as national security or personal privacy information.
If the witness says he wishes to do this in camera, I would respect that request. He understands very well what things need to be kept in private. I agree with James if he has made that request, but I don't believe he has, and I don't believe he will. If he has, though, we should be in camera. If not, then I would use the test I always use in these situations. How do I stand in front of a microphone and explain to people that we are excluding them from the public's business? In this case I wouldn't have a very good explanation.