This "video" (2nd video below) of the asteroid was generated from radar data collected on that date by NASA's Deep Space Network antenna at Goldstone, California.
Twenty individual images were used. Radar observations allow scientists to better measure an asteroid's size, rotation and location.
Radar observations of 2004 BL86 detected also a tiny moon orbiting the asteroid
The video below shows the strange looking tiny moon in detail. Streetcap1 suggests: "Is asteroid 2004 BL86 being trailed by a UFO"?