Scott, I might have missed it but you didn’t mention enabling the group metrics collection so you can see the adds/removes of the instances. If you don’t turn that on those metrics are blank at the end of the lab and group metrics collection is not on by default from what I see. I’m assuming you turned that on after you created the ASG and you changed the cool down to 60 secs.
By enabling Detailed Monitoring in the Launch Configuration, that makes it available to enable in the Auto Scaling Group definition. In the video, I enabled all these detailed monitoring checkboxes (~3:48 and ~5:00), which gives us the Group metrics.