It is Quatro
The box was printed before name was finalized
Then what are they gonna do with Jason's cover photo with Quatro on it. They're on UNO & DOS's booklets!
I'll give you this. I have absolutely nothing else than the box set to convince me that the name is iDVD!, but on the other hand, since before the box set was released, there hasn't been any mentioning of it being named Quatro. It could just as easily be the other way around. I believe the Quatro cover artwork was just used for including Jason in the album pun somehow.
But, if there is an official mention or statement of the DVD being named Quatro from after the box set was shipped, please show me