Hi
The general idea they have is OK, but they left out a lot of steps that you must perform in order to get the (pretty spectacular I must say) result you want.
Let me provide instructions that are more complete for the basic setup:
Open a new, blank slide in PowerPoint.
On the Home tab of the Ribbon, in the Slides group, click the Office Theme button and choose Blank.
On the Insert tab of the Ribbon in the Illustrations group click Shapes > Text box and then drag a text box onto the empty field.
Right-click on the border of the text box and choose Format Shape. I found these settings appropriate for the amount of text I planned to use. VERY important is to check the box for Wrap Text in Shape.

Type or paste the text you want to be read aloud into the text box. Adjust the position and size of the text box so that the top of the box is at the top of slide and the width is the same size as the slide area. Text can be and most likely will be past the bottom of the slide as much as you want.
Right click on the border of the Text box and on the Home Tab of the Ribbon format the text as white. Set the font size to something you think will be easy for someone to read as the text goes by. I went with a value higher than 48 points, but the size is up to you and depends somewhat on the display you're going to use.
Right-click on the slide background, choose Format Background and choose to fill with solid black.
Right click on the border of the text box to select the text box again, then on the Animations tab of the Ribbon, in Entry Effects apply the credits animation.
Play the slide and when you click the mouse or press the right-arrow on the slide, your animation should play.
Duplicate the slide and change the text and you have a wonderful teleprompter.