claims that GTA IV takes up just 6.32GB of the disc. They still have another 2GB free on the dual layer DVD, so that's plenty of room to add more stuff. You can look at it as them only using 75% of the disc's capacity.
And then there was this....
One of the problems with the 360, and it affects games like Grand Theft Auto if you think about how much content we put in the actual machine, is the fact that they don't have a significantly larger storage medium than the previous systems. It's a slightly bigger DVD disc.
Both Xbox and Xbox 360 support dual layer DVD, so what is this "slightly bigger DVD disc" of which he speaks?