US Navy Railgun Projectile - How it was Filmed in Flight

I did a video called US Navy Railgun, and in that video it shows a Railgun firing a projectile going length ways across the screen at up to Mach 7, yet in the footage, it looks like the camera is panning around and following the projectile the whole way. Since I made that video, I have had more than a few people ask the question, how can a camera track a projectile moving so fast. Which is a valid question, and I myself wanted to know the answer, so I investigated how it’s done and here is what I found out