buffettfan, on the SF & R Forum, for pointing me in the direction of the 2010 film "Virginia".
I had never seen mention of this film before; it stars the gorgeous Jennifer Connelly, along with Ed Harris and Carrie Preston.
Early in the film we learn that Jennifer and Ed's characters are conducting a long lasting affair, within which they are sexually adventurous. We see them looking through a sex text book, to see what to try next; they come upon a page devoted to whipping.
They take it in turns to try this out, although the images on the screen only appear pretty fleetingly. Similarly, at the end of this, ed turns Jennifer over one thigh, and spanks her. You can see enough to be sure it really is Ms Connelly, and a couple of spanks do land, but the angle chosen means you don't get a clear picture of any of this.
Still for what it's worth, here are some screen captures from the scene; sorry, I can't do video capture at the moment, and the screen is better than it looks, without ever being brilliant.
The film itself is a somewhat quirky oddball type of thing, with wildly shifts in tone; it is, overall, kind of charming though.
Hope this is all of some interest.
All the best