Audio problem: When Ron and Harry are walking down the corridor towards Potions class, Ron says, "...Quidditch trials coming up, I need to practice," but his mouth is not moving and/or not in sync with that dialogue.
Audio problem: When the trio are on the Hogwarts Express, we hear Harry say "What was Draco doing with that weird looking cabinet and who were all those people" but the subtitles say it was Ron who said that.
Answer: The purpose of the Pensieve is to preserve the memory exactly as it was recorded. Telling Harry something years after an event occurred is not as effective or as accurate as seeing. It is more impactful if Harry can watch events exactly as they unfolded. Regarding Slughorn, he had refused to give his complete memory because he was ashamed of the unintentional part he played in Voldemort's plan to create the Horcruxes. He was duped by Riddle, but he still did not want anyone to know how foolish he was.
raywest ★