If they're not connected, then they're just two antennas. What happens when you get far away from your wifi hotspot or a cellphone tower?

The voltage/energy transmitted becomes vanishingly small, and smaller than the thermal noise of the electrons in the other antenna, and undetectable. https://en.wikipedia.org/wiki/Johnson%E2%80%93Nyquist_noise

He says near the end of the video that a Part 2 video is forthcoming with more exploration of:

- Different sized loops

- Wires closer together / farther apart

- Wires on the ground instead of in air

- Current on both sides of switch

- Wires in two big spread-out loops

- Different strength resistors

The "fast plateau" is pitiful from a power delivery perspective even under tight coupling. Under looser coupling, it becomes proportionately more pitiful.