Home-burned DVDs may degrade over time and become unplayable
I have some that I burned less than 10 years ago that no longer work... the VHS tapes that I copied still play fine. Sunlight seems to be the main killer of these disks, so storing in a dark, cool, dry place may help.
I have also seen some degradation of the aluminum coating on early laser disks
Right now, I am "backing up" important video on hard drive, and sometimes SD memory chips. Very large 1TB hard drives are pretty cheap now, and will continue to drop in price... large SD memory chips are getting cheaper every day. I don't know how long the SD chips and hard drives will last, but at least they can be easily "backed up", without additional loss of quality.
jr