There’s a big problem with that, which is that we don’t actually see in 3 dimensions. Our eyes only get 2-dimensional projections of a 3-dimensional world.
Our eyes could get 2-dimensional projections of any more-dimensional world, actually, if it was available. The light-sensitive outline of that little guy in the video could accept photons from any 4-direction, and not only photons floating in his current 2-plane.
Ofc it is abstraction, I know that physicists aren't happy with heterodimensional settings at human scale.
We see in 2D, with a tiny bit of depth metadata. True 3D vision would allow you to look at someone, and see the entire volume of all their internal organs simultaneously.
The comparison here is, as usual, to go down a dimension. Imagine living in a world where everything is constant vertically, like those old 3D maze screen savers or Wolfenstein 3D. You're really seeing a 1D amount of information about a 2D world (in fact, this is how the calculation is for Wolf3D and other games of its era). You can infer depths to objects if you have two eyes.
Now contrast that to if you were plucked up vertically 'above' the game's level to look down upon it. Now you can see the entire 2D extent of the maze at once. Before, your vision was blocked by the walls, now you see the walls and what's on the other side of the walls simultaneously in a way that's entirely distinct from simply seeing through a transparent object.
Now, like seeing a 1D amount of information about a 2D maze while live inside it, we see a 2D amount of information about a 3D world around us (a picture demonstrate's this 2D amount of information - it's planar). Now imagine being lifted out the 3D plane of existence so that you could behold the entirety of the 3D world at once. That's the rough analogy.
It's somewhat like having the alpha on everything turned down to varying levels - you can see through the skin, bones and metal implants are still at 100% alpha - but fundamentally no different than what looking at someone gives you: a 2D plane.
