The most basic setup is to simply wire the QT Py GND to the negative (sleeve) conductor of the video plug, and the QT Py A0 pin to positive (tip), as shown below.
To get a bit fancier, you can create a small sandwich of QT Py, video plug, and BFF charger board, with a side of LiPo battery. This way, you'll be able to run from battery, or plug into USB C for power and charging.
You can choose to use the plug or jack version of the video terminal block breakout. These can also be swapped later.
Or, get a socket-socket adapter to allow the nub to be used in cable mode.
Assemble Headers, Wires
Solder the extra long header pins to the QT Py as shown -- Note, the addition of a second set of spacers is highly optional, it only serves to look cool.
Solder the header sockets to the underside of the BFF.
Solder a short black wire from the QT Py GND to the composite video plug's negative (-) terminal and a yellow wire from the QT Py A0 to the video plug's positive (+) terminal as shown.
Then, sandwich the plug between the boards as shown. Delicious.
Plug the battery into the BFF.
Use a small loop of Kapton tape or a small piece of double-sided foam tape to secure the battery to the header.
You can plug right into the composite video jack of a TV or monitor, flip the BFF power switch to on, and set the input to "composite" or "video".
If your monitor has a USB port you may be able to power (and charge) the video nub shank using a short USB C to USB A cable.