wow
its GREAT
not only is the animation very well done but the way you showed each instrument being played (ex: a small ball hitting the cowbell)
the music is simple and it sticks in your head and sounds great
if this were an actual music box i would definitely run out and get it myself but until then ill just leave it playing on the loop
some things i would say to improve with this would to maby add more color or maby some sort of background like a childs room where a music box would achualy be found
over all it is very well done and im positive that if you were to make other videos like this they would be a hit