There seems to be an organized pushback on this:
The DoD says those are geese, because we don't have cruise missiles that can fly in formation. At least, we don't have declassified cruise missiles that can fly in formation.
They say that the apparent high-speed flight is just an optical illusion created by a huge difference in relative velocities. But look at the first couple of seconds of film? When the camera isn't panning, the ground is not moving that fast. When they zoom in and start following the "geese," you can easily correct for the initial ground-pan caused by the flight of the AC-130. Those are some damned fast geese.
Furthermore, Geese don't fly in V's just cuz it's stylish. Each bird flies slightly above the one in front of it, reducing wind resistance. This is an early evolutionary adaption, since all migratory birds share the trait. These "geese" are flying abreast.
Finally, there are an awful lot of "individuals" chiming in on the weapons-systems blogs saying emphatically that these are birds. The likely explanation for all of these curiosities seems like a coordinated push-back to me.