Nokia added a sixth lens in the latest iteration of their flagship device. The Lumia 925 have one more lens compared to Lumia 920 and Lumia 928. The added lens is said to make the images more sharper.
The video also gives a better idea of how the optical image stabilization hardware works inside the Lumia. The Optical Image Stabilisation (OIS) works with the use of a very precise sensor called gyroscope that can identify camera movement and react to it as well. This in turn eliminates fuzziness in pictures and shakes in videos.