Setting Camera Focus on Yourself
The rule is that you always focus on the talent's eyes. Dave has made a set of portable eyes that he's clamped onto a mic stand and parked in the same spot he's going to be standing. Not only is this good for framing, but now he can check focus on his "eyes". If you have a zoom lens, zoom in and focus, then zoom out. Dave is obviously using a prime lens, which doesn't zoom. An external monitor can help you immensely when you have to check critical focus like this.
Comments
While the remote focus is a good (and cheap) solution, if the camera is too far away, you wouldn't know what result you have until after the fact.
To combat that, it might be a better idea to combine an external monitor, even the SD one mentioned on this site. With the camera's magnification capability, you should be able to find sharp focus doing that.