If anyone is going to have a problem, it’s me. At about 1:30 he uses Shift+R to see the mesh voxel size displayed on the object, but that doesn’t work for me. The first time I tried it, it just switched me to object mode for some reason, but now when I try (not sure what changed) it does nothing at all.
Edit: I was going to delete this post because after writing it I went back to Blender, tried again and it worked. But now it isn’t working again. I have no idea what’s going on.