Royell continues to ignore the fact JBC suddenly flipped his right arm upward at the same frame JFK's arms started upward and immediately after that he dipped and turned dramatically to his right. These combined movements were made in rapid succession immediately following JBC getting shot.
Within an extremely confined space, Gov Connally was beginning to "turn around" to his (R). Kinda like sitting in a armless chair, inside a phone booth, and attempting to "turn around" your upper torso in order to face the opposite direction.