Yes, the example demonstrates some other functionality of dynamic DropDowns that you wont need so much.
For your scenario, you need:
A recordset to populate the Parent list
A recordset to be used by the Create Dynamic Array server behavior.
The Parent list and the child list
Set the Parent List to be dynamic and pull records from the first recordset you create
Add the Populate List From Array behavior to the onChange event of the parent list and target the child list.