Creating a DVD with Nero7

vbimport

#1

When I use Nero 7 to create a DVD Video from a move thats say in a .AVI format I open the file in Nero if its too big for the disk Nero asks me if I want to reduce the size of the move I click yes and Nero reduces the size down to about 3.5 gigs
My question is y does Nero not make use of the hole disk
Thanks