Since this video was made, the TopUp site is no longer available. However, you can download the top_up-min.js file (referred to at the 9:18 mark of the video) here:

After you download the file to the same location as the HTML file in which you want to use TopUp, you may link to it from your HTML with this code:
<script type="text/javascript" src="top_ up-min.js"></script>

If you do not want to download the file, you can link to the js file on my server directly using:
<script type="text/javascript" src=""></script>