Re: How long do tapes and DVDs last? Seems like my VHS collection is going to hell...
Videotape, audio tape, computer diskettes - they're all basically rust on a sticky mylar backing material. Yes, they deteriorate just sitting in you cabinet. The oxide can continue to oxidize, the mylar is subject to temperature and humidity issues and can become stretched or start sticking to itself over time. And that's if you
don't play the tape.

If you play it your cause wear to both the recording surface and the mylar substrate every time you pop it in the VCR or tape player.
8 to 10 years is a pretty good average lifespan for a video cassette, as millions of people who transferred their 8mm home movies to tape and then threw the movies away have discovered to their horror.
DVDs and CDs are digital recording media read by laser beams. There's essentially no wear and tear in playing them and the materials they're made or are more robust. If handled properly and stored in reasonable conditions they
should last a good many years. Most discs will probably outlast the formats themselves. ("Looks like I'm gonna have to buy the
White Album again.")
A couple of caveats: A couple of years after the CD was first introduced manufacturers discovered that some of the inks used to silk-screen the labels onto the discs were chemically reacting with the discs themselves and gradually eating straight through the material into the data layer. Some DVDs, like laserdiscs before them, have suffered from "rot", a condition that arises when a manufacturing or materials defect causes the multiple layers of a disc to physically separate. A number of early DVD releases were notorious for becoming unplayable after a couple of years.
I believe that causes of DVD rot have mostly been discovered and corrected and that most DVDs will last a long time (much longer than any form of tape), but they aren't eternal. You may find yourself needing to rebuy parts of your collection (or transferring it to a new medium) someday. But not soon.
Regards,
Joe