Latest Bloggingheads up with Robert Greene, bestselling author of The 48 Laws of Power and most recently The 50th Law ("Fear nothing").
Excellent commentary/summary by Andy McKenzie here.
The most important piece of advice I got from The 50th Law was "always attack before you are ready".
Judging by the varying and often bad quality of video, they probably don't mail any video recorders, and by extension a microphone.
Mailing a mic and camera is the most that I've heard them mention doing. I guess that they usually just provide some video recording software, if necessary, and then wait to receive the separate video files from the participants. Then they stitch them together in post.