The video begins at the first close-up of the Hunter's visor, where you'll see through the reflection of the visor, a vertical (white) object approaching the group.
The video fades to the City, and at 22 seconds it fades back to the Hunter.
[i]Now[/i] the object is better visible on the visor, and at 26 seconds you can see the object spinning in the air and closing in, just before the video cuts to a different angle.
It looks like a block, or a flat surface of some sort.
I haven't seen anyone even mention it before, and I've been wondering about it the moment the video was out. What do you think it is? Is it important? Why is it even there? Why is it approaching the Guardians?
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The white thing is the moon's surface and the object is Earth in space.