The video was taken with LEISA, New Horizons’ infrared imaging spectrometer. LEISA's filter is designed to let in different wavelengths of light for each "slice" of the photo, from one side to another. This helps scientists study molecular variations on the surface of Pluto, since different molecules reflect different wavelengths of light - with no moving parts required.
LEISA measures infrared light, which humans can't actually see. But New Horizons scientist Alex Parker converted the color spectrum into a visible rainbow so we could get an idea of how LEISA works.
In a blog post, Parker explains that the video showed scientists that water ice is present on Pluto, and that a similar video of the moon Charon produced evidence of ammonia ice. But the video is cool, even for those of us who can't puzzle out the molecular signature of a particular patch of ice. This is the closest we'll get to a front-row seat to the Pluto flyby. In fact, you can even see the scene jiggle as New Horizons' thrusters fire to keep the little spacecraft on course.