I disagree. I think the real benefit in something like this is to is hear a discussion with a community outsider. A discussion between Elizer and Robin would be interesting but wouldn't offer anything substantially different than existing LW/OB content.
Bloggingheads.tv can't exactly call up, say, the President of France and get him to do a diavlog, but they have some street cred with mid-rank celebrities and academics. With that in mind, how would you fill in this blank?
"I would really love to see a diavlog between Yudkowsky and ____________."