Use URLs linking on the same verified URL

hello
can anybody plz explain this option to me coz i really don't get it and how effective is it 

"Use URLs linking on the same verified URL"

thank you

Imagine you post on a guestbook and leave a link. Other people will do the same but they might not post there money site link there but a link to e.g. an article site to get it indexed more quickly.

SER will try to extract all other links on that page to find possible new targets to post to.