@CynthiaEdwards1 ...
Maybe to avoid a *little* bit of confusion for your students, if you are setting up an ungraded discussion using Studio, you could just embed that video into a normal Canvas page instead of a Discussion topic? That way, since it's not graded, the interface is absolutely clear for students that the Reply button (#1 in your screenshot) is the only way they can reply to the Studio video. All of the conversation will be contained in that interface.
For the graded discussion...I realize this might not be the most ideal setup, but instead of using a discussion topic, what if you used a regular Canvas assignment and then embedded your Studio video in the assignment directions? You could still set up the assignment with whatever settings you wanted. Essentially, what I'm suggesting here as an option is a way to get rid of the confusion of two different "Reply" buttons. In this scenario, the second reply button would be gone here, too. All discussion would happen in the Studio interface. The drawback here, though, at least from what I've seen in my testing, is that the embedded video doesn't show up in the SpeedGrader, nor do the comments from your students. So, you'd have to go to the assignment page where the Studio video was embedded to view those comments...then go to your SpeedGrader (or the Gradebook) to give students a score for that assignment. Again, maybe not the most ideal, but I thought I'd throw this out as a possible work-around.
Hope this helps in some way.
