Well, you already know that it is a Membracis. There seems to be quite a lot of confusion on the species in that genus (those taxonomists again!) and loads of species have been described that are synonyms or not... In this case I think it is either what is called Membracis lunata or what is called Membracis foliata or both (and in that case it is foliata as Linnaeus was first). There is a recent study of this group available on the net if one is willing to pay ($43 ) - but I'm not - the article is here, and the abstract is free as are tiny copies of the images which can be seen here at Google. According to that study both lunata and foliata are valid, but the former should be renamed to Membracis foliatafasciata (which is considered conspecific and has priority). Membracis flexa, which according to the study is conspecific with M foliatafasciata, is described here (as is one of the valid species of the study, M fusifera). As the description of Membracis flexa fits with your movie, well...
M foliataacruata can be excluded (type is here), M celsa is described here and for M fairmairi I could not find the original description, but it included in this key (I can find no image in the study that fits that description, however). That leaves the three species that is new in the study, and there is three different types at the end (the six lower images on page 3 - quite logical to place the additions at the end). That leaves only M foliata and M foliatafasciata. As the other images come in the order that they are mentioned in the abstract, and there are gaps in the right places, and the image on this page fits with what I assume to be foliata then it has to be something close to a Membracis (foliata)/lunata/foliatafasciata/flexa/sp. whatever that is.
When it comes to the nymphs I have no idea of how to identify them except for finding images (or, if you are in Brazil, go outdoors and encounter reality) with both nymphs and adults and then identify the adults and see how the nymphs differ between the species.
To what I said above I can add this image that I found on the Italian Wikipedia-page for Membracide (which contains three more plates of other membracids1 by the way - here) - at least it is from a publication and not a mis-named/misidentified photo from flickr.com. It shows a Membracis foliata var c-album, which according to the study is conspecific with M foliataacruata (or as you call it M lunata - which according to the study is wrong, but you are of course free to consider M foliataacruata as different from M lunata). M foliata sensu stricto I believe looks like the photo I linked to above on discovermagazine.com (see below - if it is there, I cant see it now as I write - else check the slideshow on the page linked to above) and that looks like the first four animals on the first plate of the study (the plate that has a chistmas tree - or whatever it is in the upper left corner). If I'm correct in my assumption, then most of the images labeled M foliata on the net actually shows what is better called M foliataacruata/(lunata) or, at least, M foliata ssp/var foliataacruata/(lunata).
Well, enough about Membracis - I can't become an "expert" on animals I never will encounter IRL.
1Centralamerican, not Brazilian (unless they have a wide distribution)