Hi, it comes from this page, and might have been in the naked calendar thread too. Would like to know more about it myself, especially as there's some bad photoshopping of the rocks at the bottom and the side of the girls bodies.
Knows what is going on in that "scandinavian" video you posted. They talk swedish and its a student thing, at the end of the year everyone is trying to do something fun, record a movie, build a car or whatever. So its mostly just a funny thing to do, they call it "Samkväm" in swedish and its like a fun event directly translated.