It's mind. All mind.

You can also pretend you are printing something straight out of your head when you go to copy a bill.

Is this really a thing?

There seem to be quite a few pointers using something that happens for people when they consider the space behind their head. Some find it very powerful to imagine stepping out through their backhead. I haven't had that wow feeling with it, but I haven't given it much of a chance either. 

What do you glean from that?

Now you made me curious, so I started watching. Seems to be a collection of great pointers. Thankyou!

I needed this to integrate some stuff. I tend to do things in a different order than the majority, partly because I had extremely little available visual thinking and proprioception when I started out the practice. Very soon, the practice (meditation + yoga) started to develop visual thinking, so I have had the weird experience of going from being instantly boundless with eyes closed to developing the kinds of constructed limits that the practice usually deconstructs - while at the same time doing practices to deconstruct those limits. That can get pretty confusing at times. Not being able to visualize the boundaries and whereabouts of my body at all, beyond some very unprecise assumptions and extrapolations acquired from all the bumping into things and so forth, was terribly troublesome. Daily life is so much easier when the capacity to navigate a body in space is developed. Still, I miss that instant boundlessness, how it was always available. 

When Richard Lang says that he doesn't experience the body sensations as limits, I bet he doesn't mean that his experience is what mine was before. Yet, what he describes sounds exactly like what my experience was like. Listening to him brings it all back to me. I appreciate that! I think that what I need to aim at is to have either both those modes available seamlessly or some synthesis of them - or probably a spectrum of some synthesis, with seamless flexibility within the spectrum. I suspect that's how it works for Richard Lang - because if his experience were like mine used to be, he wouldn't be so content with it. He also wouldn't be able to demonstrate this with such ease, because some sense of one's relative whereabouts is needed in order to show something to a camera without messing it up (I know that from experience, lol). 

So - awesome! I'll explore how this can help me further with my integration! 

     There are a couple of interventions that cause this same effect of “void” that you mention, Stickman 3.  Hubert Benoit pointed out that by looking at your thoughts and telling them, “Speak, I am listening” thoughts stop. What remains is the image of emptiness. The other is the Open Focus technique that works with the image of space. The phrase, “Can you imagine the space (in, around,) your fingers? Any part of the body can be used progressively, or even outside the body. The result is that the mind also becomes empty. In the Unified Mindfulness system, this is called See Rest. It is a visual response that can be detected and one of the characteristics is “the relative absence of images on the mental screen. All this points to the availability of this “void” as an object of concentration. You can try to maintain it as long as possible and return to it when thoughts start up again. I see a parallel in some traditions that instruct to “turn the light around”.
“When you want to enter quietude, first tune and concentrate body and mind, so that they are free and peaceful. Let go of all objects, so that nothing whatsoever hangs on your mind. After that lower your eyelids and gaze inward.Now when you turn the light around to shine inward, the mind is not aroused by things. Next the coming and going is traceless.” Lu Yan (829-874)
​​​​​​​     It's a practice, not magic. These interventions point out that it is possible. But what do I know, I don't have a head.      

Tried this and it definitely does something but what it is I am not sure yet. As usual more research is needed

I do not experience any more 'void' than I normally do because I normally do not even experience my body/mind.
Too much cessation going on after 4th path and too much control over what I feel myself like to be of any use for the purposes of verifying something does something. All I am able to do is stating that all this is controllable so one can just do it right away when of course they know how

So my advice if you experience something would be: check if you can do it. If that already happened because of some effects any given practice enabled then it is still better to continue practice without doing this practice (of course doing it might be helpful if it actually did anything but more benefits always are from practicing it without doing it, at least as far as I can tell)

My experience with these effects are that they're best thought of as pointers. Pointers to the workings of the human perceptual system, comprised of the senses and mind. I've suggested this book before - Ten Zen Questions - which is another rich source of these kinds of pointers to ponder.

I believe Sam Harris's Waking Up meditation app (which I use) now includes Headless Way instructions and meditations.