In order to see the chart, you will need to start a simple Python HTTP server and serve the html and javascript. In order to do so, run the code in the example file, then the following in the Python REPL (Ctrl-C to shutdown):

import os
import SimpleHTTPServer
import SocketServer
import webbrowser
try:
    Handler = SimpleHTTPServer.SimpleHTTPRequestHandler
    httpd = SocketServer.TCPServer(("", 8000), Handler)
    httpd.serve_forever()
except KeyboardInterrupt:
    httpd.shutdown()
    httpd.server_close()

Alternatively, within the terminal/cmd window you can cd to your directory containing the json/html/css/js files and run the following command:

$python -m SimpleHTTPServer 8000

Point your webbrowser to http://localhost:8000/ to see the visualization.