Two days after Snowden made a surprising appearance at TED in Vancouver, the conference is giving the "other side" a chance to weigh in.

NSA Deputy Director Richard Ledgett made an appearance this morning via video link from Fort Meade, Maryland. He answered 30 minutes of questions in an interview with TED curator Chris Anderson, which was reported by Wired UK, Forbes, and the BBC, among other outlets.

Ledgett said that oversight of the NSA is real, not just a rubber-stamp, and that Snowden's decision to leak "shows amazing arrogance that he knows better than the framework of the constitution."

"He put people's lives at risk," Ledgett continued. "If our adversaries see our methods they will move away from using them. We have evidence that terrorists, smugglers, and nation states have moved away. We are losing visibility into what our adversaries are doing."

As for collection of others' data, Ledgett seemed to say that some of that would be inevitable, given that the "bad guys" and average citizens are often using the same services.

"It would be great if the bad guys used a corner of the Internet," he said. "If they had a domain badguys.com, that would be awesome. But we are all on the same network. I use the same e-mail service as the terrorists. We need to be able to pick that apart to find what we need."

The "metadata" gathered on who people call and e-mail is less privacy-invasive than people think, he stressed. It allows the NSA to be very selective about what content they actually collect. "We don't sit there and grind out metadata profiles of average people. If you're not connected to one of those intelligence targets, you're not of interest to us."

He also acknowledged that the NSA had a PR problem and said that if the agency had explained itself better, the Snowden leaks would not have been "so sensational in the media." But Snowden was no whistleblower, Ledgett emphasized.

"There were some kernels of truth in [Snowden's TED interview], but a lot of extrapolations and half-truths," Ledgett said. "He absolutely did have alternative ways he could have gone. Characterizing him as a whistleblower hurts legitimate whistleblowing activities."