Apparently it's a short film shot by himself at Kate's cottage in Cotswolds.
He's playing a new song, Kate is shown, wearing close to nothing.
And she adds her own little tidbits to his song by interrupting him by saying things like "Sonny and Cher we're not" and throwing in the word C*** and other random things.
Here's the video courtesy of You Tube. The sound quality isn't the best, but if you turn it up, you can probably hear it all.