While reading about the importance of working with the hand I also started reading about the significance of being upright.
Otis is currently in the third stage of rising to the erect posture (as discussed in The Absorbent Mind), he can stand independently if only for a moment and can walk (and run) holding onto something.
Here he is practicing standing. He sometimes practices against a wall for support but always on a bed or sofa for a soft landing. He repeats over and over.