Update: I noticed in the principled BSDF, the transmission weight in the default course files provided was set to 0, whereas in the video it is set to 1. When I changed it, the objects turned to glass as described, but the plane where they stood disappeared. It appears all objects are using the same material data causing the plane to turn to glass as well. So I created a new default material for the plane and now it functions as shown in the video.
