Tashi Wangchuk's lawyer Liang Xiaojun told The Associated Press that a judge in Qinghai province heard oral arguments for four hours and will issue a verdict at an unspecified date.
Tashi, 32, has pleaded not guilty. If convicted, he could face a prison term of five years or as many as 15 years, Liang said.
Tashi was detained in January 2016, two months after The Times published its video and accompanying article. Liang said Tashi, who has been in jail for two years while awaiting trial, was treated well in detention and in good mental condition.
Liang added that he was given ample time to present his defense, which hinged on the argument that appearing in the documentary did not amount to separatist activity.
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In the documentary, Tashi, who was also described as a shopkeeper, speaks extensively in Mandarin about the "pressure and fear" felt by Tibetans and his worry that their culture is being wiped out through the steady erosion of their language.
He notes that 140 Tibetans have died from self- immolations since 2009 and says he believes they were also protesting the disappearance of their culture under Beijing's rule.
"I want to try to use the People's Republic of China's laws to solve the problem," Tashi says in the documentary.
"If this comes to an end and I'm locked up and cannot proceed with what I'm doing and they force me to say or do things I don't want to say, I will choose suicide," he added.
He is shown seeking redress through official channels as he travels to Beijing, where he tries, unsuccessfully, to file a lawsuit against local officials and convince journalists at China's powerful state broadcaster, CCTV, to cover his case.
"All Tashi Wangchuk has done is peacefully advocate for constitutionally guaranteed rights," said Human Rights Watch China director Sophie Richardson. "If Chinese authorities consider that 'inciting separatism,' it's hard to tell what isn't."
China's ruling Communist Party often equates advocacy for greater autonomy or rights for its ethnic minority Tibetans, Uighurs and Mongolians with outright separatism. And its courts often hand down particularly harsh punishment to those criticizing the government's ethnic policies relative to other issues.
Rights groups around the world widely condemned China after it issued a life sentence in 2014 to Ilham Tohti, a moderate though outspoken Uighur critic of Beijing's policies in Xinjiang, the region that is home to the Uighurs.