For SATA 3 SSD's it can take as little as 10-15 seconds to bootup during the first month or so of a fresh windows installation, but after a while it will inevitably slow down given the user has installed a lot of third-party apps (games and the likes) and constant feature/security updates that require more loading time on startup. Though it won't add that much time, like 5+ more seconds or so. An NVMe will be just a little faster, that 12 second mark you keep talking about, but again. After a while of installing more and more apps and updates it will slow down.
Those videos you saw are probably people using a fresh install on a test machine to show you a controlled situation without any unwanted variables from third-party apps.