The gist of the video is that they aren't aggressively going after you if you don't activate. They're willingly allowing you to keep using Windows with limited restrictions and the nag watermark. Can you use Windows for free? Yeah. Is it totally legit, no, but they aren't going to stop you. Why? Is it more important to them that you use it than pay for it, because apps? Maybe. Kinda. That's the video summarized. So is Windows free? Yeah, in that context.
Realistically, Windows, tho a money machine, has been a problem for Microsoft for years. Strategically it's problematic to own an OS when you're a software company. To best serve users, and to maximize profitability, your software should be as OS neutral as possible, and that conflicts with owning an OS. In the post Ballmer and Gates era, there has been serious talk about it making it free or stupid cheap, since giving it away could generate revenue in other ways through subscriptions for related services, and app store purchases. The free Win10 for 5 machines upgrade from Win8 wasn't only a way to encourage upgrades, it was a test of the concept. That may be part of the lax response to not activating.
