I just don't get why this thing has a QR code scanner ...

Is it so that the machine doesn't need an internet connection?

You log in on your phone, scan the QR code on the game with your phone. Your phone uploads the data to the server. The machine checks the server and sees that you logged in and want to play. When your game finishes, the game uploads the data about the game back to the server, and it's associated with your account. Your phone checks the server and you can look at and interact with your game results.

That's how I would expect it to work.

But they don't keep it simple. They add yet another device with a QR code scanner when they can totally do it without one. They need a wifi dongle (which they include with the kit anyways) and the rest is software and an internet connection (which they need anyways for their current approach).

Just a quick observation with no importance whatsoever, but I still wanted to share it:
The QR code in the video reads

42 02 1b 5a 06 a2 7d 65 6d 9a 34 cf f1 3a cf 37 35 10 d3 7f 71 f0 7d 74 72 a5 25 d7 f3 55 33 60 55 b0

which in "text" would be

!µ j'ÖVÙ£Lÿ¬ósQ7÷×G*R]5S6[

and as a decimal number

1956667095441107843716972890750728168951853317041228063084830717059783886020564400

So you probably won't be able to just roll a QR code and play as someone else.

player_qr_code (resized).png