JKR: ... It's when people get really off the wall -- it's when people devote hours of their time to proving that Snape is a vampire that I feel it's time to step in, because there's really nothing in the canon that supports that.
ES: It's when you look for those things --
JKR: Yeah, it's after the 15th rereading when you have spots in front of your eyes that you start seeing clues about Snape being the Lord of Darkness.
Sooooo.... what you're saying is that Snape isn't the Lord of Darkness (i.e. totally evil), Jo? No, of course not: you're deliberately exaggerating the point so as to say nothing of substance one way or the other, because that would spoil Book 7. As indeed any sensible author being grilled by two highly knowledgeable fans ought to do.
I find the pauses and general caginess about the whole "Dumbledore knew" thing to be interesting as well. Again, Jo's response could mean anything, and basically you can interpret it to support whatever point of view you've already made up your mind to support. You can take it as evidence that she doesn't want to shoot down that theory because it's not doing any harm and she wants the fans to have fun while waiting for Book 7; or you can take it as evidence that she doesn't want to shoot it down because it is in fact what she plans to do in Book 7, but is playing casual in an effort not to give the game away.
But I do think there's something intriguing about Jo's assertion that we will learn more about Dumbledore in Book 7. Call me crazy, but I am starting to suspect that there is more darkness in Dumbledore's past than we've previously guessed at, and that part of his vehement opposition to the Dark Arts may be because he himself went a little too far down that route as a young man than he should have...
Anyway, here's the full text of Part Two at TLC for those who haven't seen it yet. I almost feel sorry for the die-hard H/Hr shippers after this one. Albeit with an emphasis on the "almost", because I do agree that from a literary point of view R/Hr was more obvious than an obvious thing, especially after GoF.