Three weeks after he was snatched from a Beijing-bound train, the Swedish bookseller Gui Minhai has resurfaced in police custody, making what activists denounced as a surreal, venal and shameful video confession to a series of unspecified offenses. “I feel ashamed about myself. I have made mistakes,” Gui, 53, is filmed telling a small group of reporters who said they had been given access to the prisoner by Chinese security officials. “My message to my family is that I hope they will live a good life. Don’t worry about me. I will solve my own problems myself.”