A classic physics experiment showing a magical physical world effect – the inverted water cup…
With a little bit of science/physics knowledge, nothing is hidden and the effect is explainable (how it works). No tricks, in other words. The trick is not only self-working, it’s also transparent. Scientific knowledge is the key to the secret.
But are the safety glasses really necessarily? Really?
Here’s the same trick, as magic:
Gimmicks…
The same physics are at work but there’s a hidden element.
There’s also a risk here that people think there is a physics explanation for the trick )(surface tension of water, for example) and the magic leaves them with a misplaced confidence or understanding of the physics…
(Penn and Teller riff on this by showing how a trick is done, breaking the secret, then rerunning the trick – with the same overall effect – but in a way that doesn’t use the secret, thus reinstilling the magic for people who think they know the secret.)
When Arthur C. Clarke wrote “Any sufficiently advanced technology is indistinguishable from magic”, which sort of magic was he referring to? The application of gimmicks, the application of trickery? Or the application of mechanisms that are transparent.
OUseful.Info, the blog... 
Sometimes the context is hiding the effect.
For example you know “the cross and the dot on a white piece of paper” to demonstrate the blindspot in your eye. I think that I saw Alan Key putting the cross and the dot on a written page… Now your brain fills the blindspot with letters, not only white space!!