im pretty sure Xehanort said he had two of the seven. mickey (in the same video) said that six are: Riku, Sora, Mickey, Terra, Aqua, and Ventus. Xehanort had Sora and Terra. yes, the seventh is most likely lea or kairi.
as for the 13 darkness;
I. old man xehanort
II. Young master xehanort
III. ansem, seeker of darkness
IV. xemnas
V. braig
VI. isa
VII. Vanitas?
VIII. terra/xehanort? (terra and terra xehanort could both be alive at the same time i think. (Lingering sentiment could be the light, and the terra/xehanort from secret file of BBS could be the dark.)
IX. ???
X. ???
XI. ???
XII. ???
XIII.???
