Video: Edward Snowden Takes Questions From London Audience

Nearly two years after his information about America's spying programs caused an international uproar, former NSA contract worker Edward Snowden spoke to an audience in London on Tuesday via live video feed.

The Q&A session was set up by Amnesty International, which says, "The information Snowden revealed has changed how we think about the technology we use" — and reshaped the public debate over governments' access to private information.

You can watch the event, above. A discussion is also being held on Twitter, around the hashtag #AskSnowden. We'll update this post with news from Snowden's appearance.

Update at 3:10 p.m. ET: On Optimism And The Patriot Act

Asked about the current status of the partially lapsed USA Patriot Act in the U.S. and controversial elements of the law such as Section 215, which covers the bulk collection of phone and business records, Snowden says:

"It's not about anything that we've struck down. It's about the fact that, despite the reality that this program was considered ineffective and illegal by every branch of government, spies; security agencies; and their representatives in Congress argued that it should remain.

"They said, but ... but ... terrorism. They played the terrorism card. They said, 'People will die if we lose this program' — despite the fact that the court says that's never been the case, despite the fact that the White House says that's never been the case: 'We need to keep it anyway.'

"And yet for the first time in 40 years ... since the U.S. intelligence community was reformed in the '70s, we found that facts have become more persuasive than fear. For the first time in recent history, we found that despite the claims of government, the public made the final decision. And that is a radical change that we should seize on, we should value and we should push further."

Update at 2:55 p.m. ET: It Was All Worth It, Snowden Says

Tanya O'Carroll, Amnesty International's adviser on technology and human rights, introduces Snowden and asks him if it was all worth it.

"It was a stressful time, I'll be the first to say," Snowden says. "But it has. It has been incredibly rewarding, incredibly gratifying."

Snowden lists the things he has lost — including his job and the ability to see his family — and he also cites efforts that have been made to challenge surveillance, saying, "We get a different quality of government when they're accountable to the public."

"It's not that every intelligence agency is evil. It's not that they never do any good at all," Snowden says. "We want to have some level of intelligence-gathering. We want to be able to investigate criminals; we want to be able to respond to military threats. But that's a very far cry from watching everyone in society without regard to their guilt or innocence — to the mass surveillance of entire populations rather than individual people."

Our original post continues:

Snowden remains a fugitive from U.S. espionage charges. He spoke Tuesday from Russia, where Snowden was granted a one-year asylum that was extended into a three-year residence permit last summer.