To me it's most definitely the flag that the man is holding in his hand on the right. He was probabaly instructed to hold the flag at a certain position until the camera panned up and over and he was to move accordingly. Only he was just a bit too slow at the beginning. Why do this? Look at the shadows... The sun is positioned in front of the camera. That's a recipe for some nasty lens flair (not always the pretty kind). When you're doing a semi-complicated camera move and trying to avoid artifacts going onto your image you need someone to block it out. It's not unheard of to have someone simply hold their hand over a lens to block out a light. Do what you need to do to get the shot.

A lens hood in a shot doesn't look like that. Il looks like a blurry, black vignette.