Complex sentence: Maureen O'Sullivan did not play the naked Jane in the alternate footage; she was doubled by Olympic swimmer Josephine McKim, who competed in the 1928 games with Johnny Weissmuller.
Split into simpler sentences: Maureen O'Sullivan did not play the naked Jane in the scene. Instead she was doubled by Olympic swimmer Josephine McKim, who competed in the 1928 games with Johnny Weissmuller.