A German company has produced a series of disposable DVD movie discs that will delete themselves after 48 hours.
In fact you can get three versions of it: a 'one-time only' play disc, 8-hour and 48-hour versions.

http://uk.gizmodo.com/2008/04/18/disposable_dvdd_discs_will_sel.html

Quote:

The DVD-D comes in a cardboard cover that will keep them usable for years but once the cover is opened, a chemical process on the disc begins that makes them useless after 48 hours. Of course, you could copy the disc within that time but then that would be illegal now, wouldn’t it? Still, with the advent of downloadable movies going mainstream in the next few years – dependent on decent broadband speeds - I see this kind of thing as a stop-gap measure to prolong DVD technology, at best.-Martin Lynch