Some of that body jitter seems to me because as one leg comes up, moves forward and then hits the ground the body dips forward and back twice in that one step. Most evident in the side view, with the constrained camera, giving a rather rapid woodpecker like motion to the upper body.
When seen in perspective from the other camera, because of the speed of those dips forward, it makes the body seem to jitter.
The constrained camera was my suggestion Rob, sorry!
But I have found it helpful at times to have but would agree it would be very difficult to do all the animating from a constrained camera. Mostly I'm in Birdseye View in the Chor and the camera that I render from always has the final say.
Forgive me Simon I maybe should have been clearer in the other thread where you asked.