From what I can find, they keys are use R not RW media, prefer DVD over CD and keep them in a cool, low humidity, pollution free environment for best results. At that I see estimates of 20-100 years. Those are all estimates based on accelerated ageing though. The media haven't existed long enough for real world results. The trick is finding the best quality media. There are different dye formulations used by various mfgs. and the name on the box doesn't necessarily reflect which company actually made the things. I'd look on some of the enthusiast sites and see what people are saying in that regard. Apparently lasers get misaligned and lose power as well so as always you probably get what you pay for in terms of burners too. With good media, and good storage the problem may be finding a working reader when the grandkid's PlayStation 12 nano-holo cube drive won't do.

Regarding compression, MS has supported it in some form since the days of DOS and sub gigabyte drives so it's there, it's free and Vicki get's downright surly when I suggest a new HDD vs. yet another bikini or that new pair of f*uck me pumps that she simply has to have. And don't get me started on the swords and constant temple renovations.
 

"Democracy is a pathetic belief in the collective wisdom of individual ignorance." - H. L. Mencken