JUDY WOODRUFF: President Obama went to Silicon Valley today to call for more cooperation between private companies and the government when it comes to defending against cyber-attacks.

In the wake of major hacks against health insurer Anthem and Sony Pictures, the president told executives they need to share more information.

But today's summit also comes amid growing tensions between tech companies and the administration over privacy and civil liberties, a point the president acknowledged.

BARACK OBAMA, President of the United States: In all our work, we have to make sure we are protecting the privacy and civil liberty of the American people. Now, we grapple with these issues in government.

We have pursued important reforms to make sure we are respecting people's privacy, as well as ensuring our national security. And the private sector wrestles with this as well.

JUDY WOODRUFF: Several CEOs of top tech companies, including Google, Facebook and Yahoo!, didn't attend, reportedly over anger and disappointment about a lack of reform in the government's broad surveillance programs.

The revelations about the government's reach are the subject of a documentary nominated for an Academy Award.

Jeffrey Brown picks it up from there, part of our series the “NewsHour” Goes to the Movies.

EDWARD SNOWDEN, Leaked Details of U.S. Surveillance: My name is Edward Snowden. I go by Ed. Edward Joseph Snowden is the full name.

JEFFREY BROWN: The documentary “Citizenfour” brings us into a Hong Kong hotel room as former National Security Agency contractor Edward Snowden reveals secrets that would make for blockbuster headlines beginning in June 2013: the large-scale collection of phone and Internet data by the U.S. government.

EDWARD SNOWDEN: Even if you're not doing anything wrong, you're being watched and recorded.

JEFFREY BROWN: News organization would publish stories of a massive database, assembled since 2006, under the Patriot Act, collecting call data from millions of phone company customers, and tapping into the central servers of major Internet companies.

For some, Snowden was a free speech hero. In the film, he explains his decision to eventually make his identity known.

EDWARD SNOWDEN: These are public issues. These are not my issues. These are everybody's issues. And I'm not afraid you. And you're not going to bully me into silence, like you've done to everybody else.

And if nobody else is going to do it, I will. And, hopefully, when I'm gone, whatever you do to me, there will be somebody else who will do the same thing.

JEFFREY BROWN: But others, including President Obama, called on Snowden to come back to the U.S. and face charges for espionage.

BARACK OBAMA: No, I don't think Mr. Snowden was a patriot. So, the fact is, is that Mr. Snowden has been charged with three felonies. If, in fact, he believes that what he did was right, then, like every American citizen, he can come here, appear before the court with a lawyer and make his case.

JEFFREY BROWN: Beginning with encrypted e-mails and then in Hong Kong, Snowden met with and told his story to journalist Glenn Greenwald, then with The Guardian newspaper, and filmmaker Laura Poitras, the director of the Oscar-nominated documentary.

I spoke to the two earlier this afternoon.

Welcome to both of you.

Laura Poitras, let me ask you, what did you want the film to do that the steady drumbeat of news revelations could not do? Why a film?

LAURA POITRAS, Director, “Citizenfour”: Well, as a document filmmaker, what I try to do is — it has all the components of journalism. It has to be truthful and factual, but really it's about saying something about bigger issues.

So, for me, this was looking at the story both of the NSA, but like what — individual stories of courage, not just Edward Snowden, but William Binney, other whistle-blowers who are coming forward. And it's also very much a film looking at journalism. So, as a documentary filmmaker, I want to make something that can be seen and be interesting today and in 10 years from now.

JEFFREY BROWN: And, Glenn Greenwald, we're watching a film in which you are actor in a real sense. How did you see your role working with Edward Snowden?

GLENN GREENWALD, “Citizenfour”: I didn't feel like an actor an all. I felt like what I was, which was a journalist pursuing a really big story.

And it just so happened that my journalistic colleague, who happens to be a filmmaker as well, filmed it because we had a good sense that this was something significant and important.

JEFFREY BROWN: The critics of Edward Snowden would look at what you were doing as collaborating with him, in a sense, working with him to bring out this story.

GLENN GREENWALD: This is a standard accusation that gets made to delegitimize journalism.

But what we did was classic journalism. We had a whistle-blower come to us with secrets that he thought shouldn't have been concealed, that the public had a right to know, and he asked us to use the standard journalistic process of reporting it. And that's exactly what we did, and we feel extremely good about that.

JEFFREY BROWN: Laura Poitras, the film plays like a thriller. How did it feel in that room? What was it like with Edward Snowden? Were you surprised when you finally met him?

LAURA POITRAS: Yes.

I mean, we didn't manufacture the kind of thriller aspects to it. That actually came with the story. I mean, I started receiving anonymous e-mails from a stranger making claims of, you know, mass government surveillance, you know, and then we met in Hong Kong.

So it actually felt very much like a thriller from my perspective. There were a lot of unknowns. So, when Glenn and I went, we were very surprised when we met somebody who was much younger than we expected. We expected to meet somebody who was in his 50s, so it took us a bit of time to adjust to that.

The person that we met was somebody who was incredibly calm in the circumstances that he had put himself in, given the risks he was taking.

JEFFREY BROWN: Glenn Greenwald, fast-forward now. Is there evidence that we can point to that collecting the data has harmed people? Is it the fear of it? Is it the idea of it, or is it — is there actual harm?

GLENN GREENWALD: Oh, there's all kinds of harm.

I mean, we have been able to report on the targeting of political dissidents, of people who visit Web sites like WikiLeaks who have their data trapped, targeting on economic conferences, on the U.N., eavesdropping on people while they negotiate trade agreements.

But, you know, I think that, more broadly, it is the fact that knowing that you live in a surveillance state chills the actions of not just journalists, but human rights activists and political organizers and lawyers and psychologists and medical professionals, people who need secrecy.

JEFFREY BROWN: And how do you see Edward Snowden even now?

GLENN GREENWALD: I see him as somebody who did what we should want people in government and with access to secrets to do, like Daniel Ellsberg, who is widely considered a hero, which is when someone like that discovers something that the public ought to have known about.

And he did that knowing that he was putting his life and his liberty in jeopardy. And to me, it's an incredibly admirable act. Democracy depends on having people like Edward Snowden.

JEFFREY BROWN: But even many people who are glad to know about the information think that he should come back, that he should be tried, that he should pay the price for an act of civil disobedience.

GLENN GREENWALD: Well, I mean, it's, I guess, pretty easy to say, well, Edward Snowden should just come back and submit to a cage for the rest of his life, but I don't really think that that's his obligation to do.

He's been given political asylum. And I think, unfortunately — Daniel Ellsberg, who did submit to the judicial system in 1972, wrote an op-ed early on in The Washington Post saying, in the United States, in the post-9/11 era, if you are accused of national security leaks, it's been proven that your conviction is virtually guaranteed and that you do not get a fair trial.

And he said, Edward Snowden is absolutely right to have sought asylum in another country because his political rights would be abused, rather than protected.

JEFFREY BROWN: Laura Poitras, since the revelations have come out, there's been a lot of talk of reforms, calls for reforms from the president, from Congress, from tech companies. Do you see any changes that have come from Snowden's revelations?

LAURA POITRAS: We're seeing a lot of changes happening in the tech companies.

I think that the disclosures have created an awareness of the need for privacy that they know the customers are going to want. So we have seen a lot of changes happening there. We see that Google is using encryption of its servers when it was disclosed that the NSA was sort of tapping into their servers.

So we have seen those kinds of changes. What we have seen less of is government changes. And then, also, Glenn and I have been reporting internationally. There's — I think, internationally, there's a shift of consciousness around the threat and dangers of the kind of indiscriminate mass surveillance that we have disclosed.

JEFFREY BROWN: And what do you want people or companies or governments to take from the film? Do you want some action from the film?

LAURA POITRAS: I make films because I really believe in the power of communicating.

And so how people then use that information, you know, that's up to them. So I do hope that it raises awareness and maybe takes an issue that's abstract and makes it a bit more human or visceral, so you can understand the consequences.

JEFFREY BROWN: All right, the film is “Citizenfour.”

Laura Poitras, Glenn Greenwald, thank you both very much.

GLENN GREENWALD: Thank you. Appreciate it.

LAURA POITRAS: Thank you.