Yes the vob files will spread across 2 normal DVD-Rs but from what I've been reading up on you'll have trouble burning it correctly, remember that we're dealing with 2 layers and you need to specify where the layer change occurs, and an iso will contain the necessary information about the layer change and how to deal with it (reading the 2nd layer from the outside edge to center - the standard for films, or the center to outside edge) because it's a full disc structure instead of just the files.