Mine is similar, not sure if you mean the dowel/chair leg method or Mikes actual contraption. http://www.homebrewtalk.com/showthread.php?t=44148
My beer has not come up out of the dowel, so I have not needed an airlock. And mine goes down into the beer so that the Brett can live in the wood, they like it there and get O2 in a similar way to a barrel.
"Did you ever kick a woman in the midsection while she was wearing a whalebone corset? I nearly broke my great toe. I never had such a painful experience." -Egbert Souse(W.C.Fields)