No, your eyes aren't decieving you, that is legit halo 4 gameplay. The main changes that I can point out is
-New foot step sounds (They are alot louder)
-New BR sound from alpha
*You can now get a good look at the hud. Look! forerunner vision!
*Game mode is called Midnight slayer
-Badges apear on screen but you also get the text in front of your screen kinda like Call Of duty or other "Modern" games
-Some sort of point system?
-Death animations (They look pretty awesome!)
-More that I forgot which are easy to point out.