The divertimento is traditionally understood as "a musical genre, with most of its examples from the 18th century. The mood of the divertimento is most often lighthearted (as a result of being played at social functions) and it is generally composed for a small ensemble. Divertimento is used to describe a wide variety of secular instrumental works for soloist or chamber ensemble. It is a kind of music entertainment although it could also be applied to serious genres. After 1780, the term generally designated works that were informal or light."
Next, from the same performers, here's Mozart's Divertimento in D major, K. 136.
Finally, here's his Divertimento No. 15 in B-flat major, K. 287, performed in Japan in 1984 by the Berlin Philharmonic Orchestra conducted by Herbert von Karajan.
Mozart wrote 27 divertimenti, and many other composers contributed their own pieces to this classical genre. You'll find most of them on YouTube. Consider them the "pop music" of the classical era.