interface a module using a 40-pin Board-to-Board SMT Connection?

As in the video, I've found that flux, copper braid and a clean soldering iron tip make a world of difference. Once those first 2 corners are soldered, doing the rest of the pins is pretty easy. The only issue I had when doing some of the Espruino prototypes was if you're rushing and press too hard against the pins and bend them slightly - but that's easy to avoid.

I'd maybe recommend that you find/make something that can press down on the top of the component and steady it. He presses down with some tweezers in the video, but I found my hands are so shaky that the chip occasionally moves around!