For the sample of Concentric Circles; Below Sequence Scale and Opacity click on Circle. Hit f4 to open up the Replicator Cell Tab. Drag you new shape into the Object Source well and you’ll see a hooked arrow. Let go of your left mouse button and your new shape replaces the old one. So if you wanted rectangles instead of a circle you could do that. Hope this helps.
Stephen Smith
Salt Lake Video
Check out my DVD Money Making Graphics & Effects for Final Cut Studio 2