Here is the link to a transcript of the interview I heard: "Deciphering the NSA's New Wiretapping Motivations": Timothy Naftali
"The White House is saying that it is very careful not to listen to point-to-point conversations in the US -- from one point in the US to another. But there is a way through data-mining to analyze where calls originate and where they go. This is basically an attempt to look for patterns, use of words, length of telephone call, length of email. frequency of these communications, both voice and data, and then to look for suspicious patterns. How do you define suspicious? I don't know. But the now deputy director of National Intelligence, Michael Hayden, has talked about their being a subtle, soft trigger. The computer learns what's suspicious and then it will act on its own. So what we're talking about is a higher order, a smarter Google, if you will."
More of the Q and A:
"SI: Does the fact that the Administration went outside the system provide further clues as to what they may have been doing?
TN: Certainly! When this first leaked, it looked as if the Administration had a certain number of problem cases, a few hundred, that didn't fit in the FISA system. But as we learn more, it became apparent that you have a program that as generated hits, some of which are US persons.
SI: And you're supposed to get a warrant...
TN: You're supposed to get a warrant. How do you sustain those investigations under the law? when the law is designed to deal with identified suspects? That's the challenge.
SI: This has been a mystery to some people. How can we be talking about current law being outdated when the FISA, by all available evidence, has nearly always granted warrants when asked. Doesn't seem like that high a bar.
TN: It's not a high bar at all if you know the name of the individual. But -- again -- what if you're looking for suspicious data transmissions?
SI: If you're just looking for these patterns you can't even ask for a warrant?
TN: I don't think so. I don't think the law is designed for that."
Of all the stories I have read or heard, I find this to be the most believable. Of course, we may not know for 50, or even 80 years what is really going on. This seems like a guess that makes sense.