They look like smaller LED screens that will surround the main video screen. It wasn't clear from the renderings what these components would be (at least to myself).
I'm pretty sure these are not the pieces surrounding the video screen but part of the screen itself. The nine of them appear just wide enough when placed side-by-side to fill on of the horizontal brackets.
I walked by today and they have finished installing the bottom small screens that will surround the main video board. They are angled and spaced exactly as you see in the rendering.