Madonna's long-time friend and producer, William Orbit, revealed an interesting thing today, on his Facebook profile...

"I get ambushed in the studio sometimes, usually after round-the-clock working. Guy Oseary shot footage in the studio a few times when I was with M, usually when we were playing over songs together on acoustic guitars.
Madonna can give me a hard time with my mixes, but is very forgiving of my absolutely terrible singing voice. I'm not so forgiving of my voice though, especially when it's immortalized on film. Perhaps I can persuade Guy to dub a proper singer onto my bits. A 'singer-double'.
But this morning I knew they were coming to film. And no singing!"