Can't "Hack" it at the end
I have been at it for many days and countless tries. I must have played the video several dozen times. I tried every combination for keying; keying in Pose mode and keying in Object mode; keying different sequences; I even tried using multiple parents. In the end, after I successfully executed the "hack", every frame behind that goes haywire.
Here is frame 90, where everything worked fine. This is the frame where the cgc-box-rig-proxy is finally put in place by the robot arm. The cgc-box-rig-proxy is moved from right to left - as was shown in the lesson.
Here is frame 91 after successfully executing the "hack". By the way, thank the person that pointed out setting the orientation to "Local" instead of "Global", to prevent the box from rotating. I left the "Empty" object in place to show the "hack". So the cgc-box-rig-proxy snapped back to the left box from the right box.
Now comes the weird part. I went back one frame to frame 90 to check, and lo and behold, the box has jumped backwards. And there is a line connecting the robot arm to the box. By the way, when I keep going backwards, the box moves right behind the arm attached to the line. If I start from the beginning, the robot arm would just animate like there is an invisible box and would pick "it" up. All the while with the actual box trailing behind it. Pretty wild!
I will keep trying to figure this out. I just don't understand the mechanism behind this. I tried looking it up in the Blender manual but so far I am coming up empty. I also could not figure out how to execute the Visual Keyframe the other person suggested. So any help would be greatly appreciated. Thanks much in advance.