There is an option in menu Add Karaoke File. You can add .kar or .mid file directly to ID3v2 tag. After adding kar file to the tag it will appear in Karaoke folder. You can select .kar files to play from karaoke folder and play it with your favorite karaoke player.
The main goal is to have Mp3 and Kar(Midi) file together in single Mp3 file so you can play either Mp3 or Kar(Midi) file. This way is easy to maintain your Mp3/Kar collection once you insert karaoke files into ID3 tags.