Nine Inch Nails also did this: https://www.youtube.com/watch?v=mDsqpeiTqg8. Which, to me, is a bit more impressive even if it is CGI. A 3d pin video screen would be massively cool. I want to say someone else did a similar music video in the '80s, but can't remember.
This version is unlikely to be able to compete in almost any metric with robot arms or even far simpler purpose-built machines (think simple 1 DOF automation used in manufacturing assembly lines, like bottling plants). With time interesting and unique applications of some future version of this might find a problem it can solve elegantly.
Now if this is efficient in any way - no idea.
Not a word about of each "3d pixel" is implemented, which is a shame. I guess it doesn't have to be too complicated, but there sure are a lot of them even in this early prototype/lab version. They're also bi-directional, with each pixel having position-sensing.
Here's a demo of one pin powered by Arduino and an H-bridge motor driver circuit: https://youtu.be/pLzDHLm01wM
Three.js software demo: http://pinthing.com
Now as it turns out, there really are linear actuators that cost about $1 per actuator, they're just tiny:
it appears they use 900 motorized slide potentiometers connected to bowden cables.
Current prices from mouser suggest that the actuators alone cost $23,000. This isn't a cheap toy, but it does show what we could do if actuators got cheap...
That way instead of just working laterally, and from the bottom, things could be done from multiple angles. For example, solving a rubiks cube via machine typically involves at least three axes and servos, but with a machine like this that operated on three axes, I imagine a more power efficient method could be developed.
This is really cool technology, I love how simple it is in design, yet it evokes all kinds of ideas in the mind.
Give me a few 1980s-vintage robot arms and I will outperform this system in any category except entertainment value. Robot arms once held great entertainment value and this system will become old media some day, too. Semiologically speaking, this system represents a silo of sublime resources from dopaminergics to labor and cash, but when the zombies come, I'll bet people will still run to the shed full of AK-47s.