If you pay attention to the video, the card sends a notification to the phone with the transaction amount & merchant information.

Knowing the transaction amount is not possible from the "sender" portion of a magstripe. You're simply handing over a credit card number. The credit card amount is negotiated over the phone/internet between the bank & merchant.

This means that the Plastc card likely has one hardcoded number that switches payments serverside. Similar to the Wallaby card or Google Wallet card.

This works perfectly fine with chip & pin. The merchant charges the Plastc card which in turn forward the transaction to the correct bank.