From my reading I understand that the comment on being able to wiretap absolutely anyone was on the basis that he was a sysadmin. He had write access to databases of people who's communications were to be intercepted in full and could add arbitrary phones or emails to them.

Binney on the existence of this list: "what they do is take their target list, which is somewhere on the order of 500,000 to a million people. They look through these phone numbers and they target those and that’s what they record." [1]

This appears to be separate from the Main Core list of 8 million Americans "which contains personal and financial data of millions of U.S. citizens believed to be threats to national security." [3]

Another Binney interview: "he [Snowden] had access to go in and put anything... If he knew their phone numbers or attributes, he could insert them into the target list which would be distributed worldwide." [2]

[1] http://dailycaller.com/2013/06/10/what-do-they-know-about-yo...

[2] http://www.usatoday.com/story/news/politics/2013/06/16/snowd...

[3] http://www.salon.com/2008/07/23/new_churchcomm/#