If you look at the source you'll find a link to a youtube video that tells you all you need to know. Don't give up :-)
Yeah, you can click it, but only if you already figured out how it works - move the fake mouse cursor to the point where it is almost over the button, blindly move it down a bit and click.
Found a fun Firefox issue where after putting FF in the background I tried to command-click that button to trigger it. My mouse cursor disappeared across the entire OS even though Firefox wasn't the active application! Had to bring Firefox back to the front to see my cursor again.