Voltage Regulator vs Voltage Divider
Took me a few rewatches to understand him. The Voltage Divider is for the FTDI's Tx/ESP's Rx line, not the power. A 5V signal on the Rx line would kill the ESP, so it needs to be brought down. Since it's an input, likely High Impedance, it will barely affect the voltage divider, keeping the divider voltage at 3.2V as selected.

The power comes from a bench power supply set to 3.3V.