It also explains why the "aliens" were disguised as rocks, as they had yet to assimilate any humans to be able to copy them. However, after killing the crews of the Soviet and American vehicles, well...
- taking it one step futher the so called "aliens" were deployed by Soundwave to kill any humans that tried to go back to The Ark.
- "Soundwave superior, Humans inferior
This explains how the video got back to earth. They may not have been watching it all as it came in, maybe it was scrambled for the DoD.
- Unfortunately for that theory, live lunar broadcasts couldn't capture full-motion, full-resolution 16mm quality. Or at least, that's what They tell us.
- Alternatively, Las Plagas are native to the Moon and were introduced to Earth by a chance meteor strike which knocked some of them loose millions of years ago (hence the Plaga fossils underneath Salazar's castle).
- As another alternative, they share a common ancestor in primordial microbes which were separated by the formation of the Moon before almost any other life form.
(As, of course, was Clover...)