I think it might be a reflection from within the studio hitting the screen behind, if you stop play the video there is another reflection towards the bottom right upright of the bridge (0:15), both coincide with the newsreader moving to his left, You occassionally will see reflections like this if someone like a floor manager or cameraman moves a monitor and the screen catches the studio lights or I think on this occasion its his white paperwork being revealed as he moves to his left , his backlight will have lit his scripts on the desk and as he moves his arm you see the edge of the paperwork, angles give the illusion of movement as his arm reveals more of the paper?
Sussed it, its his chrome armrest, his backlight is hitting it towards his left arm(camera right side) and as he swivels his chair and moves his body the reflection of the armrest moves across the screen behind. (0:08-0:10) the other reflection is the upright of the armrest.