So, it turns out this is a fairly clever (remember kids: clever doesn't mean good) of discrediting people who want to be seen as either conscientious objectors or principled. Make them go back on their word, often in public. But the videos of apologies and such that get released are really just the tip of the sword.

Their interrogation techniques have been known to be extremely brutal right up until the moment you apologize -- even if it's just two people in a room with cameras off -- because the Chinese government wants it that way. They want the rules to be extremely well known.

Everyone knows you get beat till you go back on your "disruptive" ideals. Sometimes they permanently cripple people or put them in a coma. 99% of the time, though, they release them. That way, everyone knows, when they see that the dissident is basically fine, that they betrayed their own beliefs, even if it was in private, even if no one saw.

Completely irrelevant aside: it's stuff like this that comes to mind when people talk about how dysfunctional the American government is. The Chinese government can have complex policies with parts that a lot of people find uncomfortable or wrong, and still have the whole system the way that will be most effective instead of most comfortable -- their astounding urbanization and rise in not just wealth but advanced skills and it's relation to the hukou system is a good example -- but when you have unchecked power... this is another consequence.