In order to send the follow-ups depending on order status changes with specific products limitation, you can specify the following conditions:

1. Add autoresponder or edit existing one.
2. Enter Autoresponder Identifier (this field is required).
3. Choose order status you need and hit enter.

4. When you'll choose order status you'll see additional "Start Autoresponder For" field. Simply start typing product name and you'll see the dropdown with your products listed. Choose the one you need.

5. Set other settings.
So in our example follow-ups will be send to each customer who's order is completed and who ordered product - Javascript (Definitive Guide).