I'm not going to add much to it. I would like to parrot my colleague, Monsieur Godin. Having somebody by video conference or by teleconference is absolutely not the same as having them in the room. You don't get the same impression.
Furthermore, my experience in committees with respect to the person on teleconference is that they tend to end up being the lesser witness, the lesser person, in terms of the attention the committee gives them. I think that does them a disservice.
I certainly think it's an important and valuable tool so we can have people who would otherwise be incapable of appearing before the committee, but having witnesses in person is critical.