This setting is the radius of the Ball. Minimum size is 10 and maximum is 100. A smaller ball will bounce faster. By default, this setting is 50. This is the setting to double the visual size of the underlying desktop that will be shown during the bounce.
Enlargement is based on the center of the display.
By default the desktop is not enlarged. Focus Turning focus on will warp the horizontal axis of the ball to the left edge of the circle, giving it a lens effect. This looks really neat. By default this setting is off. This is a recurring theme in screensavers.