Mr. Ruiz moves his hand toward and around the window, apparently trying to rule out the possibility that the image is a reflection from within the cabin. However his hand only blocks reflections coming from the extreme left of the window; it does not rule out reflections coming from above and behind him - which is where cabin lights would be.
At one point the lights suddenly disappear, likely because a passenger or airline attendant passed (unnoticed) behind the cameraman and in front of the cabin light being reflected.
Further support for this explanation can be seen when the video shows an outside wing light, which looks very different than the "UFO." This is what a true light outside the fuselage looks like: one single coherent light (complete with minor lens flare), not a double-reflection of small, scattered duplicate lights showing no lens flare.
Because interior airplane cabin lights are designed to point downward and not across the aisle, it makes sense that the reflected light would not be one single light source (such a spotlight effect), but instead two or three smaller, irregular lights incidentally reflected - and duplicated - in the window.