Except that as I said, Jessie was practically right at the top, so there wouldn't have been many stairs to run down in the first place. And I think the pause in time does matter, as it shows that for several moments, they're just running around and the explosion hasn't really peaked yet, just the uppermost parts starting to blow and pieces starting to fall. But there was likely at least a minute or two in between that and when Barret found the wire given that they had time to stand there and gape in the first place. Just barely enough for Cloud to have gone back for Jessie while Barret searched for an escape route. No reason they couldn't have done both at the same time. And remember, Cloud's bound to be a little faster than the average person because of his Jenova enhancements, not just stronger.
And there's no way to tell from the trailer if the staircase-blowing moment in the remake happens before or after you reach Jessie. It's possible, due to certain dialogue at the start of the TGS trailer that we only hear but don't see said, that she actually makes it up to the top with Barret alive and unharmed this time and her end comes there and not on the stairs. It's just a guess, but in the trailer, Tifa called out to both Barret and Jessie but we never actually see her doing it. Then Barret responds, again without us seeing him talk, asking her where she and Cloud have been, which could be from the moment they reach the top of the pillar rather than the ghost attack in the slums where the dialogue plays over in the trailer. But dialogue tends to be mixed up and rearranged in trailers, so it's a good bet it doesn't actually come from the ghost attack scene at all. And later in the trailer, we see Barret and Jessie running up the stairs and leaving Biggs, Wedge, and some other folks behind. The last we see, Jessie is a little ahead of Barret on the stairs but they're both past where most of the fighting seems to have been going on. So it's possible she's there with Barret this time when Cloud and Tifa reach the top.
