OK, so now that you've seen and are beginning to understand the concepts - it's FINALLY time to start applying some of those concepts to a real piece. Suggest you find some blanks to play with - say a half dozen 3/4 x 3/4 x 6 inch blanks - maple or cherry preferably.
We'll be playing with Four Centers, Two Axes and Two Arcs. We'll start with two Parallel Axes and a single Axes Plane - then add some TWIST - just to make things a little more interesting. Note that twisting requires that your two axes DON'T ACTUALLY INTERSECT. THAT's important. (Look at where the centers are located in this illustration - until the "light bulb" goes on - and stays shining brightly)
If you have questions about any of this stuff, feel free to e-mail me at email@example.com.