I admit it. I am a legitimate hater of karaoke. But doesn't this raise some licensing issue for those using it in a commercial setting, say a bar? Or does Apple set aside that issue on their licensing agreements?
The owner of the bar has to pay ASCAP/BMI/SESAC license fees for public performances of any kind. It doesn't matter of the karaoke is coming from CD+G discs, a hard drive, iPods, or anything else.
Commercial actually doesn't affect this much - only the fact that the performance is public. Whether or not the bar chooses to charge a cover for admission, they still need to pay (the amount they pay, however, does change, depending on these circumstances.)