48V, 10A at 6 feet or less length requires 16awg wire for <=3% loss (which is the critical appliance standard rather than the more lax >= 10% used for most DC circuits). That’s a wire with a conductor diameter of 1.3mm ~= 0.05in.

The cable probably isn’t 10A rated. But, it’s not an overly thick wire to get it done. Most of the girth is insulation and shielding.

This is overly simplified. And, I didn’t care to watch the video.