Solving graph connectivity problem from 4Clojure.com

Lots of people had questions about some of the medium and hard problems on 4Clojure, and since class only meets once a week I thought I'd make a screencast walking through my solution to one of the similar problems in the hopes that this would help some. The problem I solve here is the graph connectivity problem (http://www.4clojure.com/problem/91), which is similar to several of the assigned problems. I've also posted my final code as a gist (https://gist.github.com/4662080) in case that's helpful. This is pretty roughly edited because I wanted to get it up and out there ASAP. I did cut out nearly 10 minutes where I got totally lost in the weeds due to a simple misspelling ('closure' instead of 'clojure').