Editor's note: TED is a nonprofit organization that distributes "Ideas worth spreading" through conferences and talks available on its website.

(CNN) -- One month before Chinese artist Ai Weiwei was detained by authorities in his country, he made a powerful case for free expression in a film shown at the TED2011 conference in Long Beach, California.

The 53-year-old artist was shown talking about the limits on freedom of speech in China. At the end of the film, he was shown on a live webcam waving as he acknowledged the cheers and standing ovation from the audience at TED.

Ai Weiwei was detained April 3 at the Beijing airport, as he was about to travel to Hong Kong, and authorities later said he was under investigation for suspicion of "economic crimes." A spokesman for the foreign ministry, asked about Ai Weiwei, said, "It has nothing to do with human rights or freedom of expression."

In the film, the artist said, "I'm living in a society in which freedom of speech is not allowed" and pointed to the blocking of Facebook, Twitter, Google and YouTube. He said searches for his name on domestic websites were blocked and that he was constantly under surveillance.

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Introducing the film, TED curator Chris Anderson showed some of the artist's works, including the Bird's Nest stadium, which he helped design for the Beijing Olympics, an exhibit at Tate Modern in London of more than 100 million handcrafted porcelain "sunflower seeds" and a series of photos in which his middle finger is extended toward symbols of national pride and power such as the Eiffel Tower and the Forbidden City in Beijing.

"In recent years, Ai Weiwei has become increasingly critical of the Chinese government and has faced consequences for that," Anderson said. "He's had exhibitions canceled, he's faced beatings and his beautiful new studio in Shanghai was bulldozed on January 11." Anderson said Ai Weiwei couldn't attend the conference "because of his current circumstances," but had secretly recorded the film.

In it, Ai Weiwei said he had been trying to connect his art to social change to encourage people to be more involved in society and "to help China to become a more democratic society."

After the devastating earthquake in China's Sichuan province in 2008, he mobilized people through the internet to investigate and document the deaths of students in poorly constructed buildings. He said he was "always trying to remind people that an individual can make an effort and also can make an impact."

The artist noted China's great strides in growing its economy and becoming more connected to and recognized by the world community.

"Still we are still a communist society," he said. "Basic values such as freedom of speech and human rights are still in poor condition. Many people -- only because (they) speak their mind -- they can be put in jail or can be put in a very difficult situation." Ai Weiwei said Western nations are tolerating a lack of human rights in China. "This is very shortsighted and will not help China to become a modern society."

Eventually, he said, change will come. "Nobody can really avoid that."