Interesting! Looks like it's bundled as a single HTML file (and then hosted on Github Pages). [0]
From the DataMapPlot Docs [1]:
"While the interactive plots work well in-line in a notebook, it is often useful to be able to send plots to others. The save method allows you to save the plot to a single HTML file that will embed (compressed) copies of the data. You can then share the HTML as required."