I think you misunderstood my question. I am talking about asking the Set-top Box that question, not yourself, so that YOU have to take the action to back up the video, turn on the closed caption, etc. . . but that Siri will hear your question and take care of it for you, automatically. No, Roku cannot do that. As you said, I don't believe a $49 gadget will not have that functionality. If it cannot handle answering a question during playing a film, it obviously cannot handle this.
As Steve Jobs is famous for having said, "You don't win by skating to where the puck is, you win by skating to where the puck is going to be."
An unusual allusion for a nerd/Zen Buddhist/Vegan who despised sports. IN FACT Wayne Gretzky said this
Wayne Gretzky I skate to where the puck is going to be, not where it has been. My Account Help: ... A good hockey player plays where the puck is.