This might be a stupid question, but I was wondering if there is a specific origin to it, or if anyone could hash up the earliest of videos that first featured it.

also seen in countless other videos such as Can't Hold Us Down by Christina Aguilera

Isn't that more of a theatrical/dance technique? I dunno, Pat Benatar "Love is a Battlefield"?

I thought the point of it was to get both tits AND ass in one shot.

seems like an old film noir kind of thing to me.