videos in AudioSet
A list of about a million ten-second YouTube clips, each labelled with the sounds in it, that Google published in 2017. Labs use it to train and test general audio and music models.
Including Wolfgang Amadeus Mozart - Piano Trio in B-flat major, K. 502, 2nd mvt., Evanescence - My Immortal (piano quartet version, ft. Jun Sung Ahn), Yoshi's Island - Flower Garden (piano, beatbox, and ft. Josh Chiu on violin!)