Thanks for comments. In the video I used some Python to smooth the camera target (and the camera). Using a target camera on a jerky dynamic object gives too much camera shake. Here's a simpler version of a smoothed camera target using XPresso
https://www.dropbox.com/s/2621hewmm0g7edj/smooth.zip?dl=0
XPresso soft target would probably achieve the same, but I've had problems with it in the past.