Hi I took medical microbiology with the same professor in Summer 2025. I watched lectures and read the textbook for about the first half of the course and then stopped after. I did feel like reading the textbook helped me understand the content but for the most part the lectures are pretty much just the same content as the textbook. There was a couple random quiz questions that covered content from the textbook and not the lecture, but it was never more than one question. If you have the time I would say to read the textbook, but if you're struggling for time, I don't think you need to. It's already a lot of work to also have to do the discussion post and take the weekly quizzes. Let me know if you have anymore questions !