I didn't watch the video, i rather not see anything of the game anymore. On Reddit however someone says 1080p apparetly is a rarity according to DF. If true, i'd find that weird, i recall 343 in a interview saying it would be 1080p most of the time and only going lower when shit was getting hectic. But then again...maybe the game is nothing but hectic, hmmm.
What i am about to say is only based on the E3 video and the b-roll video after that, but that didn't look like a world of difference graphically compared with Halo 4 from TMCC. That game was 60fps too (except for some framedrops here and there, right?) So i guess the real big difference is that these levels are indeed MUCH bigger and are simply much more heavy on the action?
Again, i have not watched any other videos, none of the first three missions, so it's very possible that it looks a lot better than Halo 4 in those though. But if not, i'm just surprised that we get things like 30fps in some animations and those AF...''issues''. No disrespect meant towards the developers at all by the way.