It seems that the original development of mythnettv has stopped. I have been maintaining a branch of my own, just to scratch some itches I had, as I use it to download such shows as TED-Talks and SLOW TV. The following is a list of changes I have done to the code since release 7 (January 2009) by Michael Still, that might interest you:

• the command "mythnettv statistics" is now much shorter. I have commented out most of the "what has been downloaded" part and only left "what will be downloaded".
• downloads which are stored in a folder are handled a bit better, but some more work needs to be done. Only single file video files in a folder are currently supported. 
• no transcoding is done for most modern, linux friendly file formats, as they are well supported by the internal player within MythTV 0.24.
• neither commercial detection nor seek table creation are done anymore, as MythTV 0.24 then screws up playback of some web content.
• some basic detection of subtitles, audio (mono, stereo etc) and video (widescreen, 720p etc) properties is done while importing. This metadata is inserted into the database to be displayed as if the file had be recorded with valid EPG data.
• a new command line "myhtnettv updatemeta filename" allows you to update the database retrospectively with the above data. This also works for "normal" recordings made by MythTV, if your EPG data was not accurate for these values.