China recently executed two people for their parts in the riots last year in Lhasa, and now is prosecuting a movie maker. The movie showed regular Tibetan people expressing their love of the Dalai Lama and heaping scorn on the Chinese authorities and the large number of Han moving into their lands. The man who made it, Dhondup Wangchen, knew that it was likely he'd get arrested (and so sent all of his family away to India for protection). Supposedly, he has been tortured, but the Chinese government has not allowed anyone to have access to him.
Why does this matter for East Asian security? Every outrage like this gives more credence to China's greatest boogeyman, the Dalai Lama. How can China dispute the words of the Dalai Lama if they constantly do exactly what he accuses them of? Moreover, though the Tibetans have long been more pacifistic than the Uyghurs (and, despite what the PRC government says, the Dalai Lama is more pacifistic than most), there is probably a limit to the amount of pushing and repression.
The other thing to keep in mind is that the biggest sticking points between India and China is Tibet. India shelters the Dalai Lama and his entire government-in-exile. The other big sticking point is the exact boundaries of Tibet vs. India. The more tension there is between the Dalai Lama and China, the more tension there will be between India and China. It really is in China's best interest to reach SOME kind of accommodation with a guy seen as one of the holiest men in the world.