Yes, it was a Sesame Street special. the full title is Sesame Street's All-Star 25th Birthday: Stars and Streets Forever", and it was broadcast on ABC on May 18, 1994.
This was the 25th anniversary special, The plot involved a man named Ronald Grump (played by Joe pesci and based on Donald trump), who wanted to tear down Sesame Street and build a Grump Tower, and a news reporter, kathy Lee Kathy (played by Julia Louis Dreyfus and based on kathy lee gilford) covered this story. The special featured many clip montages, and special appearances by various celebrities, such as danny devito, rita pearlman, regis philbin, kathy lee gilford and more. some of the clips included in this special included the original version of being green, jim carrey demosntrating happy feet, the celebrity version of Monster In The Mirror, cookie monster driving a train in Beat The Time, the adults seeing mr. snuffleupagus for the very first time, and much much more. Like in 20 and still counting and the other 25th anniversary special, this one ended with the cast singing "sing".