Selecting Tween Frames
You can select any frame on the timeline by left-clicking on the appropriate segment in the ruler at the top of the timeline window.

In the editing window the tween will update to show the position of all objects at that point.
Related Topics
Tween Object Overview
Tween Properties
Tween Timeline
Creating the Tween
Shape tweening
Adding Objects to a Tween
Deleting Objects from a Tween
Adding Keyframes to a Tween
Removing Keyframes from a Tween
Moving Keyframes in a Tween
Copying and Pasting Keyframes