Adulttv | | Next Episode for SmartPlaylist?

Hello,
I'm trying to implement the In Progress TV Shows widget for a generic SmartPlaylist.
For example, a KidsTV SmartPlaylist grabs files from "/video/kidstv" whereas an AdultTV SmartPlaylist grabs flies from "/video/tv".
However, I can't seem to get the In Progress feature that shows the next unplayed episode for only episodes in that playlist. Anybody know how the default playlist is implemented or a good skin that makes this easy?