Going back to the original problem statement of detecting people passing through a doorway, a cheaper solution would be to use a PIR sensor. You could also use a combination of reflective IR sensor to sense the direction of travel - exiting/entering as done traditionally in automatic subway entrances.
Please let us know about your progress!
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The cool thing about that capacitive stuff is that you can still use it as a switch. When you walk past it, the lights could go on, but upon touching it the color/brightness could change. Also, I think itâs less prone to being triggered by pets, although Iâve not yet tested that with a PIR. Depending on how big/sensitive your electrodes are, you could detect the direction by checking in which order they get âactivatedâ.
What I personally think is the coolest, is the fact that you can hide it completely. Depending on what material youâre using, you could mount it on the backside, and still use it. That makes for great demos where the âinvisible magical electric thingies make stuffz happenâ, whereas with a PIR you would go like:âwell, duh, it just sees you :(â 
It may be a while before I get around to this project as I have a few other projects with higher priority than this one. The main reason I latched onto the electromagnetic field sensing shown in the video is that I perceived it to have a lower failure rate than a PIR sensor. With PIR sensors one would have to be careful to position the sensor correctly such that there would be no way to pass through the doorway without the PIR sensor seeing the person. In addition, PIR sensors can be easily fooled by things such as a thick winter jacket which would absorb the IR pulse. On the other hand, with electromagnetic field sensing, as long as the sensing circuit is as tall as the door, there would be no feasible way to pass through the doorway without being seen (i.e. no need to be careful about locating the sensing circuit).
The bottom line was that, I perceived the electromagnetic field sensing to be much more fool proof than any cheaply available PIR sensor. Perhaps that is a rash judgement on my part, but in my experience PIR sensors are very easy to fool.
Looking back at the video, it does seems like a very nice and nonintrusive way to detect people! and I bet one could make artsy wall decals to go with it. Now I feel like I should order one of them ; )