Teenwire.com is Planned Parenthood's site for teenagers. It has excellent accurate information on sexual health, everything from info on STIs to discussions of whether it's more difficult for overweight girls to date. I just noticed today they have a video called You've Got Your Period - How to Use a Pad, Tampon, or Cup! (I can't link to the Flash video, but the link is on that page).
I think that's kind of awesome :) I love that it doesn't try to push cups, but simply presents then as an equally reasonable option to pads and tampons. And it mentioned reusable pads too! I have some minor niggles in that the animation makes the cups look huge, but none of the other products look too realistic either, so I guess it's no big deal.
P.S. I highly recommend their 'How To Use A Condom' and 'How Pregnancy Happens' videos. Absolutely excellent site, and they just got even more brownie points from me.