Whichever interpretation, if in doubt best to ask moderators about concrete example about it. In my experience, in these forums belonging to same group, such practice is at least frowned upon and I will not post direct links to stuff like that.
I think that when you agree to the terms of the MS Insider Program, you agree *not* to share the builds. So, posting leaked builds is technically against the rules, and frowned on in this forum. We want legit MS links here.
I looked for the agreement last night, but since I'm already a member, I couldn't re-sign up. However, Microsoft has a Pre-Release agreement that most of us must sign before downloading and installing Beta (Technical Preview) products. I just don't recall whether I was required to sign one for Windows 10, although I should have been and probably was. I was required to sign a new Pre-Release agreement on Microsoft Office 365 2016 only a couple of days ago.