Got a working implementation of Play Next Episode Of {show name}
Put the attached .xsp in your smarts folder and use this command:
<command id="150" name="Next Episode of {1}" enabled="true" alwaysOn="False" confirm="False" requiredConfidence="0" loop="False" loopDelay="0" loopMax="0" description="">
<action>
<cmdType>XJson.SmartPL</cmdType>
<params>
<param>smarts\nextepisode.xsp</param>
<param>{1}</param>
</params>
<cmdRepeat>1</cmdRepeat>
</action>
<action>
<cmdType>TTS.Speak</cmdType>
<params>
<param>Playing next episode of {1}</param>
</params>
<cmdRepeat>0</cmdRepeat>
</action>
<action>
<cmdType>VC.Pause</cmdType>
<params>
<param>500</param>
</params>
<cmdRepeat>1</cmdRepeat>
</action>
<action>
<cmdType>XJson.Raw</cmdType>
<params>
<param>Player.Open</param>
<param>"item": {"file":"special://profile/playlists/mixed/voxsmart.xsp"}</param>
</params>
<cmdRepeat>1</cmdRepeat>
</action>
<phrase>play</phrase>
<phrase>next episode of</phrase>
<payloadFromXML phraseOnly="True" use2partPhrase="False" phraseConnector="by" Phrase2wildcard="anyone" optional="False">XbmcPayloads\xbmcTvShowTitles.xml</payloadFromXML>
</command>
And boom! The next unwatched episode of the named show will start playing.