Originally Posted by Roger Dressler
If anything, it's the opposite. They lose value because it is easy to obtain a copy.
See an ebay listing for out of print DVD's, particularly for films with true artistic merit, historical value, or almost any music performance related DVD.
In the case of music performance DVD's that are out of print, their value usually increases (for any artist I've ever been interested in), even though they are trivial to copy.
Same for out of print Disney DVD's and lots of others.
Once un-watermarked original CD's ad DVD's go out of print, I am certain the value of original un-watermarked CD's and DVD's in private collections will increase for the majority of CD's, most music related DVD's, and a majority of film DVD's. There are always exceptions, but by and large, I believe this will be the case. The current data on ebay/craigslist clearly demonstrates this.