I can hear you all now though...
"But Jon," you say. "I think internet downloading is hurting all of the record industry..."
Well yea, but it hurts Al even more and here's why...
Most people use Kazaa to download the singles or songs they know from an artist. For Al, its slightly different. They hear he's got a new album, they find out what songs he's parodying, then they download the ones they are most interested in. A simple search on Kazaa shows a lot more copies of the parodies available than the originals. Let's face it, most people know Al for his parodies so that's what they are going to be interested in. By the nature of Al's music, people aren't going to spend $19 on his album when they can get all six songs that they really want to hear from Kazaa.
On any other artist its like "Well I have the single, its good so maybe I'll get the CD." For Al, though, its like "Well I have the single, but there are only five other parodies worth downloading on the CD so I'll just get those and save my money."
Anyway, that's my theory.
-jon