if i recall correctly, you used to be able to start with the full web and refine by just blacklisting... now i see that if you try to make it past the step you linked to without entering any websites in the "sites to search" field, it gives the following message: "You must enter 1 or more websites."

i haven't read the docs recently, but it does appear that they have restricted this product since it first launched.

sorry if i have led you astray.