It is incorrect. A macroscopic object in a superposition like that is theoretically possible, as in the famous example of Schrodinger's Cat. But the environment around it immediately destroys the state. Looking at it would require shining light on it, and that would be the end of the state.
Quantum computers rely on such superpositions. It has proven extremely difficult to make them.
I have watched the video now. I take it back. The video is correct.
tldr: See the last link at the end of this answer for the flavor of what "vibrating and not vibrating" means.
I had in mind a chunk of metal, say the size of a crowbar. Putting that in a quantum superposition like that is theoretically possible, but not remotely practical. But this is not really your everyday macroscopic chunk of metal. While it is way bigger than an atom, it is way smaller than a crowbar.
And even so, it was difficult to put in a superposition state. It had to be carefully isolated from its environment. It was in the dark, in a vacuum, and very close to absolute $0$ temperature.
As Aaron O'Connell said, the metal was both vibrating and not vibrating at the same time. So what does this mean?
One of the comments linked What exactly does Aaron D. O'Connell's experiment show?, which does explain it. But I expect you might want a more intuitive explanation. I will try, but quantum mechanics is notoriously counter intuitive.
It is not that hard to put a single electron or photon is a superposition, so we will start there. First some background.
It is often said that a photon or an electron is sometimes a particle and sometimes a wave. While an photon is similar to a classical particle and a classical wave, it is really something different. I explain some of that here. How can a red light photon be different from a blue light photon?. An electron has mass and moves slower than light. But the same idea applies. It is something like a particle and something like a wave.
More massive objects are more like a particle and less like a wave. But even you and I have wave-like properties, even if we can't detect it.
So what is this dual nature? A classical particle is a point. When it moves, it follows a trajectory. You can say exactly where it is and how fast it is going. On the other hand, a classical wave is spread out. It doesn't have a single position. It may be composed of many frequencies. Each frequency may travel at a different speed. Up close, thunder is a sharp crack. If it arrives from in a distance, it is a rumble because different frequencies arrive at different times.
Thinking of an electron as a particle or a wave is sometimes helpful, but often misleading. Like a wave, an electron doesn't have a single position. It doesn't follow a trajectory. You cannot say exactly where it is and how fast it is going. But in a way different from a classical wave. I explain how it is different here. Does the collapse of the wave function happen immediately everywhere?.
When a photon encounters a screen with two slits in it, it passes through both slits at once. It interferes with itself on the other side. If it encounters another screen, you see a diffraction pattern. This is what we expect from a wave. For a photon, the slits need to be small, not too much larger than a wavelength of light. But you can easily make them.
An electron also has a wave nature. You can also pass it through slits and see a diffraction pattern. But the wavelength is much smaller, about the size of an atom. Electrons have been diffracted by the space between the atoms of a crystal. An electron can go through multiple "slits" of that size at the same time.
A crowbar is much larger and has a much smaller wavelength. We cannot make anything with slits so small that we could see quantum effects from being in multiple places at the same time. And of course a crowbar would not fit through such slits.
It was an achievement to see quantum effects from a tiny diving board. It was in two places at the same time by both vibrating and not vibrating at the same time. But this doesn't really mean what it sounds like. So what does it mean?
A photon passes through two slits and on the other side forms an interference pattern. Before it hits the second wall, it is in a spread out state with maxmima in some places and minima in other. But this isn't what you see when a single photon hits the wall. You see a single spot light up. The interference pattern tells you where you are likely to see the spot and where you are not. If you repeat the experiment many times, you will see many spots in the maxima. The maxima will be bright.
And it is in this sense that the diving board is both vibrating and not. While it is in the cold dark vacuum, it can be in this state. But when you probe the vacuum to measure how it moves, you find that it is in one or the other. You can never see it in both.
One more link along these lines. Schrodinger's cat was an example by one of the founders of quantum mechanics to illustrate how weird all this is. It remains useful to this day. In this example, a cat is both alive and dead at the same time. Here Veritasium explains it and uses it to illustrate the Copenhagen and Many Worlds interpretations of quantum mechanics. Parallel Worlds Probably Exist. Here’s Why
