W. A. Mozart - Eine Kleine Nachtmusik

Composer: Mozart
Piece: Eine Kleine Nachtmusik (Serenade No. 13 for strings in G major)

The first melody is one of the most famous themes by Mozart and it is really good. It's not, however, the best part of this piece in my opinion.
My favorite part is from 0:35-0:48. The build up with the tremolo notes going higher and higher in a crescendo before the music gets absolutely amazing.
The whole piece is great if you want "a little night music. It has a light and happy tone and it's brilliantly composed.
I don't know if the video shows all the four movements, or if it's just one movement, but it works well on its own.

I hope you like it :)