This is a long time after your post (and you likely got your answer - I hope ), but the code for the screencasts are posted along with the videos on the PluralSight site. For this screencast, the sample code can be found here.
As for using Workflow Services, there are other screencasts for doing this. As an example, check out the one on using the WF 3.5 Receive Activity.
(BTW - I really wish we had the ability to be notified when comments were posted...but I digress )