Advocate.com have published a clip that just looks like an outtake from the shooting of the Vogue video. Their sources say it is from an unreleased Nike commercial:

The clip finds the Madonna making fun of her late ‘80s Pepsi scandal. In the video footage Madonna has her arms covering her bare chest, looks at the camera smiling, and says, 'I wear what I want and I do what I want. Ask Pepsi.'
With the last remark, the entertainer references the 1989 controversy, in which she was paid a then-record $5 million as part of an endorsement deal, that included the filming of a commercial for the soft drink. The deal was scrapped by Pepsi executives due to threats of protests from right-wing Christian groups, such as the American Family Association, due to perceived sacrilege in her 'Like A Prayer' video, now considered one of the creative high points of Madonna’s storied career. The singer was allowed to keep the $5 million and her commercial aired only once on network television.