Ah sorry. So there are three coloured buttons. When you hold one, the site takes a series of photos from your webcam, and assign them to that "class". Then it'll train and start classifying your video input live.
It's a pretty neat way of creating a reasonable training set of 3 classes.
It's a really well put together demo & tutorial.
I held a pen up next to me and held the green button.
Then did the same with a mouse.
It would flick between the two if I was holding nothing, so I held the orange button for a bit while holding nothing.
Worked pretty much every time.
Training is fast enough with a few hundred images per class that I didn't notice any delay.