I don't think the higher security access literally means that you (the viewer) can get higher security access; it's just an excuse for keeping certain details about these species unknown, most likely because the writers didn't get permission to add to the AVP lore.
In the extras for this set, there is a section where there is a mock-up of a database held by "The Company" detailing all knowledge of both species. There is a statement somewhere - I cannot remember where - that states certain material needs a higher "security clearance" to view, and sure enough there are sections where video content is indicated, but "access restricted".
So I am assuming (possibly incorrectly) that the video in question is Out-Of Mux Asynchronous PIP footagethat gets downloaded via BD-Live 2 to local persistent storage, and probably requires a passkey to access.
Where do I get the passkey from? There is no mention of it in my box set - either that or I am blind & stoopid. Any help here would be greatly appreciated.