I... think I get it. For those who are TL:DW (Too Lazy, Didn't Watch), this is what the video means
There are random portals generated throughout the world with a certain block as it's floor. When you go in a portal holding a block, let's say, cobblestone, you will appear at a portal with a cobblestone floor. And so on and so forth.
This idea has potential, but there are many unexplained points. For example, how do you activate the portals? Are they inter-dimensional? Can mobs walk through them? Please elaborate.