Apple Motion 3 - Manual (Page 399)

Chapter 5 Using Behaviors 399
For example, if you apply the Random Motion behavior to a shape, that shape might
weave around onscreen with a completely random animation path similar to the
following:
If you turn the Random Motion behavior off temporarily and create an animation path
using keyframes, you can create a completely predictable and smooth movement.
You can combine the two by turning the Random Motion behavior back on, with the
end result being an animation path that follows the general direction you want, but
that has enough random variation in it to make it interesting.
While this example shows how you can combine behaviors and keyframes to create
animation paths, you can combine behaviors and keyframes for any parameter.
Random animation
path
Keyframed animation
path
Random animation path
combined with the keyframed
animation path