I thought the two characters in the flashback were younger versions of Biggs and Jessie, but who knows. It's not like FFVII is a game with no plot holes at all. Oh, and (FFVII and AC Spoilers)Rufus died in FFVII, and it was also quite implied that Tseng died, but they're both alive in FFVII AC, so I wouldn't be too surprised if Biggs, Wedge and Jessie appeared in some FFVII prequel/sequel/other spinoff. Or Cloud could see them the way he saw (AC Spoilers)Aeris and Zack in AC.