Im thinking that is an air bubble on the uTube video....If you have ever used a screen protector you know what Im talking about...At that angle it produces a glare not a camera. On a camera lens you would have an addition glare from the middle of the lens which is not seen. With stage lighting such as this and tilting back and forth this is not seen.
http://youtube.com/watch?v=j6Yt2DakywI
http://youtube.com/watch?v=j6Yt2DakywI