Rav Elyashiv on Modesty

Someone sent me the following video:

elyashiv3 from elimand on Vimeo.

A transcript of the conversation (which does not appear to include all the nuances) can be found here.

I have so many questions about this video, I hardly know where to begin. I find the attitude of the questioner extremely puzzling; it seems to me that he is incredibly patronizing towards Rav Elyashiv and relatively disinterested in what Rav Elyashiv actually answers, moving immediately to his next question. Is this my imagination?

And did Rav Elyashiv say that a Beis Din appointed by the Gedolim would be halachically binding on all Klal Yisroel?! Which Gedolim would have to be in that Beis Din for this to be true? Would there have to be Sefardim or Chassidim? Did he say that this applies to dictates regarding tzniyus that are issued by the "Mishmar haTorah" Beis Din under discussion? It's not clear to me.

Does anyone have any light to shed on any of this?