Apple Users

Both governmental and private; I'm entirely glib about this one since I suspect it's there as legal boilerplate* and, dead serious here, to make participants feel special, part of a "secret club".

Given that the product is entirely compiled, finished, complete software that has exactly the same access restrictions as the release version (an Apple ID), I doubt there's much in there that Apple would, or even could, go after a user for sharing; sure, it's all technically walled off by the agreement but the gate in the wall barely has a latch, let alone a lock. Can't really say the product isn't "general public knowledge" when the general public has unfettered access to it.

* - Ok, so if the beta of 10.10 has some nifty new core technology like launchd, Grand Central Dispatch, or timer coalescing (most of which are open-sourced anyway) and somebody went through the trouble of decompiling and working out the details, I could see Apple dropping Mjolnir on them, and that probably is why the NDA is there, but that's a pretty specific and implausible situation.