Not to sure what to think of this really ... can't be a round because if it were you would be able to see it go across the entire frame. Atleast a
round that huge.
I have no idea of what the object is but the disappearing act is just down to bad editing. I have looked at this frame by frame and once the object
disappears the very next frame there is a jump in the film so it appears that they cut a chunk out of the original clip.