The showmanship is, indeed, impressive and beautiful. I enjoy all three performances (although I could do without the microphone to catch the golden-diapered performer's dramatic breathing). But I'm deeply cynical about how much concentration is actually required.
Note that the three performances are not just the same
sort of act.
They use the very same set of palm ribs. (The performers in the two videos to which I linked are father and daughter.) Only the feather is different.
I know from my teaching experience that it takes a long time for kids to achieve
the ruler and hammer illusion for the very first time. But if they then mark exactly the right spot to place everything, the feat is easily reproducible, and no less miraculous to the audience.
If the kids were to go so far as to put a subtle groove into the ruler and the hammer handle, so that the string and everything else could hang together perfectly, without slipping from the balance point unless actually jolted--the equivalent of the notches and pegs I see on the palm ribs in this act--it would be even more of a no-brainer.
The slow, tentative, carefully calibrated movements needed the first time would now no longer be needed to manipulate the items themselves; they would mainly be manipulating the audience's appreciation for the near-impossibility of what the performer seems to be doing.
I think the real miracle is that these performers are able to hold the audience's delighted attention for so long. Even mine, when I'm so skeptical of what's going on. Again, a testament to truly masterful showmanship.