So Twin Peaks cameraman Manolo Rojas, who also worked with Gaga, Britney Spears and Mariah Carey (he says he was very disappointed with Mariah because of her diva attitude), granted an interview in which he speaks about how was filming with Gaga on G.U.Y. MV. It's no big thing but I found it interesting. It's in Spanish, Gaga's (and Mariah's) part starts at minute 49, so I've translated and summarized it for you. Sorry if my English is too bad, I've tried to make it understandable.