This is a write once read infrequently archiving system. Perfect for creating your ultimate movie/music/video collection. Though they do not state so explicitly it should be no trouble to keep a index of files and use it as a online archive with high seek times. Meaning you could have a 600 DVD online archive of any data with a total possible size of 2.8 terrabytes. Which come to think of it - isn't really cost effective now that hard drive prices are low. Well, it looks cool and would make a great conversation piece.

The price for a hard drive is about 23 cents/gigabyte
The price for a dvd is about 5 cents/gigabyte.

So its still possible for DVD's to be more cost effective, you just need alot of them.