“Flight of the Bumblebee” is an orchestral interlude written by Nikolai Rimsky-Korsakov for his opera The Tale of Tsar Saltan, composed in 1899–1900. The piece closes Act III, Tableau 1, during which the magic Swan-Bird changes Prince Gvidon Saltanovich (the Tsar’s son) into an insect so that he can fly away to visit his father (who does not know that he is alive). wikipedia
This is a piano transcription played by Maksim Mrvica a wonderful Croatian pianist. It happens to be one of my favorite Youtube performances of the piece. It has gotten almost 7 million views!