Personally I don't think that kind of approach is a great idea as coding isn't really a performance activity - I prefer letting people work on a task in isolation then discussing what they have done afterwards. YMMV.

Edit: Also, and I do mean this constructively, some people can be pretty intimidating on a 1 to 1 basis without knowing it. I only realised this when I was in a CTO position and had some training where I was videoed in meetings and I realised that a lot of what I was doing was actually pretty rough on people....