I agree wit Dave, get the skipDoctor or something close to it, just get the automatic one, the hand one where you crank it and spin the disk yourself, isn't all that well built and it sometimes slips which will cause skid marks on the disc. Well they aren't exactly skid marks but that's what the remind me of. You won't be able to buff those out no mater how much hand work you put into it, I've tried, several times. Though I haven't seen anyone have problems with skid marks yet but the ones I caused were really small, but they look weird on the disk and if they are big I have the feeling that they would screw up a disk, as the line it's not so reflective. I have both now, but at first I thought, I'd just buy the hand held one, and have tiny arm workout, while getting scratches off my disc, well I got the arm workout a bit more the what I expected, and the scratches were gone, the disk plays wonderful again, just I got skid marks on my disc where the dumb thing slipped while I was cranking on it. Not to mention I have yet to find a good body position to crank it. The handle and crank are just in a very odd place for me it's not all that comfortable to crank on the darn thing for 3 to 5 minutes straight in a very awakward position. But then again that might just be me, on the odd position thing. But all the hand crank SpinDoctors do skid or skip, and if it's a Cathe DVD, get the automatic one, who would want their Cathe DVD to have skid marks on it, from the dumb thing slipping it's own gears. Espcially if you just tried to get all the scratch marks out, I myself kind of found that frusterating when I tried to fix a DVD, it wasn't a Cathe, but it was one I loved, I got the scratch out only to put skid marks on it.
But I'm sure we'll never have a DVD with disc rot from Cathe.com, her workouts are just too good to be put a cheap disc, and discs that they usually come on, are very high quality, at least from the few tale-tell signs I pick up in Physics class, from playing and destorying DVD and Cds, if that means anything.
And yes you are correct it is best to avoid finger prints and scratches all together, especally if it happens to be just after your workout and your hands are a little sweaty and you touch the bottom of the DVD, you can touch anywhere on the clear plastic rim, but the bottom that is where the data is, and sweaty fingerprints can be corsive depending on your bodies chemestry. And they always leave prints which is actually oil from your body. Which if your a DVD, it means your ditry. It's just like finger prints on a nice clean window or mirror that part that was touched isn't as clear or reflective as the nice clean part. And when your depending on reflection so your workout will play, you may not be happy to find out, it was your own fingers that stopped your workout. That was another fun experiment I did in Physics, how many finger prints and where will mess up the dvd playing ability.
Kit