The image of the cell layers of the retina at 0:12-0:15 is reversed. The photoreceptors should be at the very back of the retina; light must travel through the other cell layers of the retina before reaching the photoreceptors. Below is a corrected image. Note that the images throughout the rest of the video (after 0:15) are correct.
Light must travel through the cell layers of the retina before it reaches the photoreceptors.