What I'm doing here is I take a shape (in this case an octahedron, which is a double pyramid), and I make it in to a rounder object. Every iteration I add 3 vertices (corners) and create a triangle from these (that results in 3 more triangles). I make sure these triangles get the position they need to have so the model becomes more round. In the video I do this for 6 iterations total (the model most left is the basic shape).
A real world scenario for this could be models that get more detailed as soon as the player comes close, so that it wouldn't take as much rendering power to render objects far away.
This all was done in Unity3D with C#, though not much Unity libraries were used.
More info on davidschep.com - May 19, 2016