I have been using it for so long, I often forget that it isn’t default Blender functionality!
It is an addon called F2, which comes with Blender but is not enabled by default. You should be able to find it in the Addons part of your preferences. I would highly recommend enabling this, as it will increase your modeling speed exponentially. In the video, you will actually be able to see that I have pressed the “F” key to create faces with just one vertex selected. It also requires context of your mouse position to know where to create that face, and will require a bit of trial and error to get a feel for how to use it. I guarantee that once you get comfortable with it, however, you won’t know how you modeled in Blender without it!
