Looking down the second floor stairwell, the camera zooms in. I could have used a single frame and resized it to create a zoom-in artificially, but the parallax effect is what makes the zoom-in believable. Granted, using Houdini would have resulted in a smoother parallax effect, but since the rest of the animation is jerky and odd, a smooth segment would stick out stylistically.
Compare the two clips: the second one is smoother than the first. The second clip was constructed by layering, staggering and blending the original in four iterations. Although the movement in the second is smoother, we lose the crispness of the original.