Well, I don\'t know if they will eat up a lot of data, but I doubt it eat it as much as CG movies in video format, such as in high def in MPEG-2, MPEG-4, or VC-1...
Remember, HD-DVD now supports up to 3 layers, each with 15 GBytes in prototype. and last I checked, HD-DVD can support up to a total of 4 layers. Giving you a total of 60 GBytes.
But of course, Blu Ray still beat HD-DVD in the storage area.
Blu Ray supports up to 8 layers, each with 25 Gbytes, giving you a total of 200 Gbytes...I remember reading TDK created a 4 layers 100 Gbytes prototype blu ray disc about a couple of months ago, and of course they are all compatible with current 2 layers Blu Ray player/reader...