The blobs are saved on the Cydia server so when you go to restore, tiny umbrella re-routes iTunes from looking for the apple server for blobs, to Cydia.
And perhaps a little nicer language. Edited ~ I don't see a problem with jackass. It's an animal. Let's stay on topic. SP
As for downloading, the os will always be available on this forum, so no need to rush. But, when you download 4.3.4, iTunes deletes 4.3.3 from your computer.