The first several songs on the Spotify player above are from Piano Man (Legacy Edition), and then the Live on WMMR Concert begins.
Full Album (Audio) - Live at WMMR Sigma Sound Studios
Other Early Concerts
Billy Joel, Al Hertzberg, Larry Russell, and Rhys Clark play a mini-concert at a soundstage at Southern Illinois University in 1972 for the university television program "The Session." They drove through a snowstorm to get there, and by that time the audience had left, but the crew was fortunately still there and taped the footage. The video was formerly on YouTube.