Normally, the system boots up, you choose your Mii, your game icons appear, and the system goes into the game.
With this, your game icons appear, you choose your mii, the system boots up, and then goes into the game.
The only difference is the order of events. The time needed for each of them to occur is exactly the same.
No, you're missing out on something here. The actually OS has to be booted up in the normal way. The way in the video completely skips that step.
You boot the Wii U. It loads up the OS, you pick your Mii, it loads the Miiverse + icons you can pick from including the game you have in. In the video, you pick the game, your mii, and it loads up all the functions it needs to run afterwards and then runs the game immediately afterwards.
You see the step that's missing now, right?