The feather movement observed at 2:56 in the documentary may be attributed to residual vibrations from the release mechanism and internal forces within the feathers. As the feathers hang, these forces create minor oscillations that take time to relax after release. The upward motion seen in the external parts of the feathers could be a result of transmitted vibrations or air resistance, while gravity causes the edges to droop. In a vacuum, the stresses on the feathers would be eliminated, leading to a different behavior. The discussion draws parallels to a mass on a spring, illustrating the time lag in movement after release.