Structure
1.  Notice the top line remains level and the head is carried at a 45 degree angle while moving, indicating well laid back shoulders.
Improper shoulder set or short overly muscled necks would prevent the dog from carrying the head high with confidence and would instead give the look of trundling.  Without proper angulations, hip and shoulder set, improperly overrechiing or shortened reach and/or drive are exhibited.
Judging movement is a fine art.--we are looking for the dog that moves perfectly, smoothly and efficiently from the side and down and back.
1.
2.
2.  Length of upper arm (humerus)...Judges can assess length of upper arm by using  three reference points that can be easily located.  The top of the dog's shoulder, the point of the shoulder, and the tip of the elbow..
A structural problem where the upper arm is shorter than the scapula is becoming  commor in the Rottweiler.  This causes a particular movement fault typically resulting in less than optimal reach when moving and less than optimal convergence toward the centerline.
3.
4.
4.  Length vs. height:  The body is just slightly longer than tall.  The proper points for height are the highest point of the scapula at the withers to ground.  For length the proper points are the point of the shoulder where the humerus meets the scapula back to the end process of the ischium (not the buttocks itself or the croup). 
point of shoulder
Withers
Buttocks
5.
5.  Moderate and elegant neck, jawline well above backline.
6.
6.  The shoulder blade (scapula) is long, wide, muscular, and well laid back.  The upper arm (humerus) is roughly equal in length to the shoulder blade (scapula) and joins it at an apparent right angle.
The stifle angle matches the croup. 
Drop a line from the rear most point of the buttocks perpendicular to the ground...correct angulations this line should fall directly in front of the toes of the hind foot. 
7.
7.  The Planes of angulation passing through structure.
Viewed from the side, the hock joint is well bent and the rear pasterns are perpendicular to the ground.