FYI the Start button doesn't seem to be working for me with Adblock turned on.
If you check the JS console log, you'll see that this is most probably caused by calling the Mixpanel (analytics/tracking script) track method in slideshow.js (line 12), which triggers an error because Mixpanel is not loaded.
Here's the error: 'Uncaught ReferenceError: mixpanel is not defined'.