Download Flash file here - Control-click and choose Download linked file as.... Save to your Documents folder or your USB drive (or both).

Here's how to do it:

Create a motion tween following previous directions.

Click on the Add Motion Guide symbol under the list of Layers in the Timeline. Click in Frame 1 and use the Pencil tool, draw a line from where your symbol begins to where it ends. Click on Frame 1 of the Layer that contains the motion tween. Drag the symbol so that the dot in its center touches the beginning of your line. Click on the last frame in your Motion Layer, and move the symbol so that its dot touches the end of the motion line.

Play your movie.