Actually, I don't see anything unexplainable, and I'm fairly imaginative. It's a well-known fact that our manned orbital spacecraft are
accompanied by "swarms" of ice crystals — these are produced by vented gasses, orbital maneuver thruster exhaust and, unfortunately, jettisoned
human sewage. So any given manned orbital mission is going to be "followed" by a cloud of its own icy debris. The use of maneuvering thrusters is
well-known to disturb the debris cloud, sending ice crystals careening off in all directions.
NASA has been working for years to reduce the amount of icy debris accompanying our manned missions — accumulation of ice can be potentially
hazardous to extended orbital missions as well as to vehicle reentry.
Now, what I see in this footage is a camera trained on an Earthly lightning storm on the dark side of the planet. That's the primary subject of the
footage. I can see ice crystals moving slowly, right-to-left, out of shadow on the right; these ice crystals are briefly illuminated by reflected
light from the spacecraft (apparently the craft is approaching the Earth's morning terminator); and then the crystals pass back into shadow.
Once again, ice crystals provide a source of consternation and wild speculation.
— Doc Velocity