Perhaps it's an object that hit terminal velocity and then reversed
this is fake.
The force it had on the trajectory away from the earth became equal to the gravitational force. So the velocity became 0, then the gravity pulled it back down along the same trajectory.
I have a logical answer.
Perhaps it's an object that hit terminal velocity and then reversed, there's no way of determining which way is up and which is down. Perhaps the trajectory was away from the earth and the camera was rotated at an angle.
No, for terminal velocity only occurs within an atmosphere. It is the poitn at which the air hitting the falling object resists it's velocity by the objects weight force that basically means that the wind blowing upwards equals the weight force of the object and thus, the object cannot accelerate anymore and is relying on its momentum. In space, there is no atmosphere, so no terminal velocity.
The simple movements here look like 'retrograde' motion. Without any info on the film I do not think it is fair to assume that this is shown in real time.
The changes in brightness might mean that we are seeing the object from a different position relative to the sun.
If this is a real time video I'd guess we are looking at ice or paint flakes separating from the shuttle. The shuttle is moving relative to these particles and the relative motion is perceived by the viewer as a change in position of the particle when this is more likely movement of the shuttle and the camera.
For the UFO folks out there I have to admit - this is a great UFO shot.