that's not the enterprise bridge dome. there were some great hi-res images of the 09 bridge a while back and there's a big ball shaped object that is suspended in the center of the dome with no balcony.
i will see if i can find those shots.
Compare also the bridge panorama which was on the official site from the time of the first movie:
Whatever we're looking at in the screencaps linked here...
... it's somewhere other than on the bridge - looks to be a larger, more open area.
Liking the Scotty clip, though, and liking Pegg's take on the character more each time I see something new.