zoomBlur() smears the picture towards a point, as if the camera rushed at it: speed, a dash, an impact. center is the point, from [0, 0] (top left) to [1, 1]; strength is how much of the way to it the smear reaches, and samples how many reads of the frame make it up (at most 32).
It reads the frame smoothly between pixels, so the smear is a gradient rather than a row of copies.
Move the pointer to place the centre, ↑ ↓ for the strength and Space to switch it off.