Does anyone know what kind of buttercream she uses in this video?
That's Sharon Zambito aka Sugarshack (here on CC). She has 3 recipes here on CC depending on the size of your mixer (just type in Sugarshack's in the search field when you are in the recipe section. The PP posted one of her recipes for you.
I would also highly recommend getting her videos you can't go wrong with them. You can find them on her website at: