Burning size problem

Hi,
I tried to backup my copy of S.W.A.T. onto a dvd-r using DVD Backup and DVD2One X, then burning it using Toast 6. I used this method with success on my other DVD's.
The problem I have is when I attempt to burn the disc I get an error saying that there isn't enough room on the disc, 7 GB required 4.4 GB available.
When I Get Info on the Video_TS folder created with DVD2One X it shows a folder size of 3.9 GB.
Why then when I drag this folder into Toast does it seem to think it's 7 GB?
Any help would be appreciated.
Thanks,
Bob