A family of Microsoft word processing software products for creating web, email, and print documents.
Just be aware that the solution presented in that first video disables far more than Copilot. Further, it impacts features in all office programs, not only those in Word. The provider of that video doesn't bother to mention that. See this Microsoft Support article for details: Connected experiences in Office
Copilot is like almost every other tool in the software — just because it's there doesn't mean it has to be used. I'm not crazy about it either, but the feature is dormant unless a user chooses to take advantage of it. IMO Disabling Connected Experiences is like throwing the baby out with the bath water.