This image appears to be authentic, and if so it is an excellent daylight video of a disk. It was shot from the window of an airliner over Iran. It is not a reflection or a cloud. On close examination, it is not moving at the same speed, but briefly speeds up and slows down as it streaks across the sky.
Story Source:
Dreamland Video podcast
To watch the FREE video version on YouTube, click here.

Subscribers, to watch the subscriber version of the video, first log in then click on Dreamland Subscriber-Only Video Podcast link.