[anamax]

What if I want "shared MS Word" (presumably online) or "collaborative MS Word docs"?

If signing up is complicated enough that a video is a reasonable way to explain it, the signup process is broken. Why not fix it instead of explaining it better?

Why have sign-up at all? Why not let new users "start a doc and tell people about it", which should be very simple. After they've established that they can do what they want, biz users will then ask "how do I protect my docs?".