On Saturday, Chai Jing, a former television journalist from China, released a feature-length documentary film that, unusually for China, took the government to task. Titled Under the Dome, the video featured Chai giving a presentation on stage, using both photographs and slides to examine how China's notorious air pollution got so extreme—and why the Communist Party has failed to fix it. Jing's interest was personal: Her daughter underwent surgery soon after her birth to remove a tumor that, Chai claims, was caused by pollution.

Under ordinary circumstances, the Chinese government might have swiftly removed the video from Youku, China's YouTube, before it could gain much traction. But the film has been left untouched, amassing tens of millions of views and touching off a spirited discussion online. Under the Dome, which is embedded below, has even received praise from senior government officials.

“Chai Jing’s documentary calls for public environmental consciousness from the standpoint of public health,” Chen Jining, China's environment czar, said. “It deserves admiration.” This isn't how the Communist Party normally reacts to videos that criticize its governance.

The government's reaction to Under the Dome is particularly noteworthy given that under President Xi Jinping, who took office in 2013, government suppression of the media has intensified. In addition to maintaining long-held bans on Facebook, Twitter, and other foreign websites, Beijing has cracked down on any private networks that provided a workaround to the Great Firewall. And in something of a throwback to the Maoist era, the Communist Party has even promoted a song praising Internet censorship on state-run television.