I was mistaken in that the big DVD CDG was made by converting CDG'S using POWER KARAOKE DVD BURNER- and not NERO; and I apologize for my error-- IT contains only many song tracks .
Now we are cooking by Gas!
I have made a few DVD's with Power Karaoke DVD and it doesn't, if I remember correctly, generate a "standard" DVD format, i.e. VOB files.
It seems it combines the CDG graphics + the MP3 audio files into MPG files.
I've found that I can get about 230 tracks (about 16 standard CDG discs) on a single layer DVD.
It's other function is to create a simple "Menu" style interface to make finding the tracks easy.
If you look at the DVD with Windows Explorer, you should find loads of MPG files and simply double clicking one should fire up media player and you'll see your Karaoke track appear there, complete with audio.
Unfortunately, I don't know if there is any software that will convert back to CD+G.
I've replied to your other thread, Re. the Power Karaoke forum and you might get some answers there.
Please note the comments above are from memory and I'll need to check a Karaoke DVD when I get home to confirm.