Mirror of Dreams - Extras: Chapter 16

The slinky dress looks something like this in my mind :-) 
But perhaps a tad more see through, lol!

 And then they do a tango :-D 
I have a couple of possibilities for what they could have done:

 This is the more likely dance because if you discard the music in the video, the dance itself is somewhat simple, and thus could have been danced to music played by amateurs.

That said, they weren't really copying a routine here, so they could have been dancing any or all of the steps in these examples too, lol!

Ahhh... So sexy... :-D