This is just be being excited and noticing little details. Im sure most of these have already been discussed or are probably inaccurate, so I apologise 
1)01:55 - If you look at the team scores, there is a Unicorn emblem on the blue team and a Wolf emblem on the read team. Perhaps this has something to do with the new Fiction created around these teams for multiplayer? Or maybe its just the emblems of the highest scoring player on each team…
-
02:08 - “All old enemies, weapons and vehicles have been updated graphically”. Does this mean that the covenant are in Halo 4’s campaign?
-
02:20 - Blue/Black visor = Return of visors in customisation?
-
02:38 - I get the feeling they’ve introduced the thrusters as a primary ability in MM that you can use like the Jump Pack in Star Wars battle front. Perhaps pressing RB will initiate a short burst of energy that will thrust you up into the air for a bigger jump?
-
03:09 - Recording the sound of an LMG. I Hope this means theyre finally introducing an LMG type weapon in the game. HOWEVER, it is far more likely this is just to be used for turrets and on the warthog
-
03:14 - pause. There are two symbols with the number 5 next to them. Perhaps two types of new grenades. Not really sure what they could be…
Sorry that most of these are most probably stupid and redundant. PLEASE POST ANY OTHER SMALL DETAILS YOU HAVE NOTICED 