The first stage fires some retro rockets to rotate it and prevent it from re-contacting the second stage. I suspect that as the second stage was a dummy stage, the rotation occurred somewhat differently from how it would in a "normal" launch.
I woke my 4 year old daughter up for the last minute of the countdown, and the launch. She really enjoyed it

I had two video feeds running on the laptop, including one from the VAB for an alternate view.