Again, I've only ever seen this at gamestop. I've seen the trailer hundreds of times, I assure you my eyes haven't decieved me. Stop by your local gamestop and check it out (and then don't buy anything), because I sure can't find this clip anywhere.
(NOT THE SPHERE CENTURION FROM THE GAME INFORMER SOUND PREVIEW)
http://www.youtube.com/watch?v=jOby2xcV1to&feature=youtube_gdata_player
Here it is. Shot the footage myself.
Here's the link to Gamestop TV's official feed if you feel like waiting for the half-second clip of the newly spotted enemy. It's after the Top Gear racing clip and Comic Con, but if you're interested, I won't stop you. http://storefinder.cbsoutdoor.com/videopreviewservice/viewer/preview_selectstore.aspx