Breaking down trailers into a step by step analysis, or even just viewing them in slow motion, can reveal a lot of interesting information about upcoming games.
Did you notice, for instance, that Nintendo DS on the multiplayer battlefields of Black Ops II? You can totally play Pokémon with it in case you're bored in between kills. You probably saw the tomahawk that was thrown in slow motion, but did you know that it's actually the Connor perk, a reference to the upcoming Assassin's Creed III? This guy is a genius detective! Genius, I say!