Doug, I am not sure if it adds more to youtube's that you saw, but just in case :
http://www.e-cognition.net/pages/MotionSkel.html
- Can there be more than one sketch in a motion skeleton?
/ sure, you can put as many sketches as you want in Design Skeleton inside motion skeleton assembly. When body skeletons are later created curves connections are analysed regardless are they from same sketch or from different ones. So in general you can create any 3D structure to simulate real mechanism. - How can I integrate a motion skeleton with other skeletons?
/ first thing you create regular Design Skeleton inside Motion Skeleton assembly. This Design Skeleton can contain both surfaces / curves that you will later user for top down in a regular way, and Sketches for motion purpoces - both can be controlled by layers and not really interfere with each other. - Can I use surfaces or other non-curve geometry with a motion skeleton?
/ actually not, even non-sketched Curves will not make it. Sketch has the plane that is used in creation of connections. You may note that Body Skeleton has 2 type of features in it : " External Copygeom that copies selected curves, and Axis features created through end points that are used in automatically created connections. Creation of these axes requires sketch plane for normal definition.