UFO Stalks Airplane! Hong Kong to Kunming City?

Our team would like everyone's opinion on this footage below - is the photo real or fake?
I'm undecided myself and very interested in your feedback. Please comment:
 

An unnamed passenger has passed on a photograph of what appears to be a UFO stalking a plane. The picture is taken from the window of a commercial passenger jet.

The disc-shaped object was captured on a flight from Hong Kong to