Hi Phil,
Patrick is demonstrating how the Model Mode can screw up the cube, as it scales it to zero and no way back, as he shows it - while trying to pull it back.
The suggestion is to be in Object mode instead.
Try this, create a cube and make it editable by pressing the c key. Go to the Structure Manager, and scale in Model as well as in Object mode. In Object mode the point values stay the same. The information is safe for animation, even in extreme ways like scaling it down to zero. It can be “brought back”, as it was never lost. Not so much in Model mode, where the points would get zero perhaps at one point and since scaling is just a vector multiplication* of the point values, if zero any factor to this would result in zero.
All the best
*the vector (the scale value) that multiplies each single point value, takes the origin axis of the object and multiplies each point.