Maybe there is a variable bit setting for burning in
Nero. Don't really know as I haven't used Nero for DVD burning but this variable bit setting (in effect its a way of compression) is the way that standalone
home DVD recorders such as Panasonic, Pioneer, Sony etc., achieve the 1, 2, 4, (6 or 8), hours recording
on a single DVDR. This corresponds to setting the speed to XP, SP, LP and ELP on the home recorders.
Nero would have to have a programme to do this otherwise you are stuck with the maximum of 2 hours
on a standard 4.7GB DVDR.