This is a no-drift camera, which allows you to pitch to a very low level, with the added bonus of making the camera focus like The Sims 2.
In Sims 3, the camera focuses on a sim's feet. If you right click their portrait to center them on the screen, they're actually taking up the top half, sometimes not even showing their head- because the camera is centered on their feet.
With this mod, the camera centers on their torso, just above the belly button- just like in Sims 2. Remember zooming in all the way and seeing their torso? If you zoom in all the way in Sims 3, you get a nice view of the floor. Not anymore.
Here is where the camera would center by default. Note that the center of the image is the bottom of the sim- under the chair.
Here's where it centers with this mod.
Here is full zoom on a standing sim before...
And here is after.