Note on the tutorial video:
Most people have used the old duplicator(The one before this..), and know how to move the build. The thing that catches most people, and confuses them, is the part on pressing "Enter" to actually select the build. People usually try to move the build, but end up changing the selection. In other words: I find it odd how it was not explained that you should press enter to /actually/ select the build, as opposed to pressing numpad keys (to move it)to select it(In stack mode).