From the video description:
The Sprint missile was part of the ABM or Anti Ballistic Missile system. The missile would carry a 20 kiloton warhead and would travel at hypersonic speeds to find and destroy an incoming enemy ICBM.
Watch as the missile approaches speeds upward of Mach 10 in 5 seconds. The missile begins to glow from air friction. The ABM system became functional on October 1, 1975 for one day and was then shut down.