UFO spotted flying over Auckland New Zealand

Just a quick post on this one.

A strange UFO has been spotted on film flying over Auckland, New Zealand.  The video was shared by UFO Sightings Daily.

The clip shows a dark disk-shaped craft moving slowly across the clouds during sunset.  Then what looks a like an explosion appears before the craft turns and heads back across the clouds.

Check out the video

Could it be a plane with the explosion being afterburners or just the sunlight reflecting of it? …Or is it a real UFO?