Carbonfiberboy 

Not over-reached. Note that upper arms make the appropriate right angle with torso before the adjustment. The right angle is important to reduce shoulder stress. The problems in the photo are that the saddle is too far forward and the back is rounded, Reach before adjustment is correct. Bars of course would have to move aft the same amount as the saddle is moved. Especially considering the weight of this torso, the saddle should probably move aft a good bit. Shortening reach and ruining torso and arm angles is not how we reduce weight on the hands.

Besides that right angle, another good check for appropriate reach is that with forearms horizontal, elbows should be in front of knees. Weight on hands should be reduced by saddle position until the hands can be lifted from the bars without sliding forward on the saddle. Hands should be light on the bars. Then bye-bye shoulder, arm, and hand pain.

Note how little the rider's back angle is changed by this shortening of reach. Therefore clockwise torque in the video has not been reduced and my statics analysis of torque around the saddle is correct

Also, it's not the back muscles that should support the torso. It's the lats. Simple test: stand ~3' away from a table. Put your hands on the table with elbows well bent, no pressure. Your back is supporting your torso. Now push down with your hands while relaxing and straitening your back. Your lats are now under tension and you are now in the correct cycling position. Riders get sore backs, not from supporting their torsos, but from the tension in the whole posterior chain. The harder you hammer, the sorer the back. Now one could argue that the torque around the saddle provided by hammering has reduced the weight on the hands and allowed the torso to be supported by the back, not the hands. That's the same thing I just said, but looking at it another way.. It's the same thing. Really, if you're going very hard, you should have to pull up on the bars.