:

I think they reused a CEA terminal Flood cry in there, and there's a Flood infection scene, just without the CG Flood added. I'm excited for it though.

And then the bits before--either a flashback, or there's some sort of Elite terrorist activity right at the beginning? Looks like an unlit plasma in the final shot of the Elite falling, and there's Locke running after that Spirit (btw, I <3 Spirits, so yay.)

The worm thing has to be Lekgolo, I would say, although why they'd mimic a human is beyond me. Still cool that we're seeing them "out of the armor" after all this time.