As in the last arietta, the theme isn't developed on, just sung to. Like with most themes, development comes later on in the scene, which in this case is but sketched yet.
For those expecting more developed, flashy and dynamic stuff, be patient. Not everything is a showstopper. Demo #4 is expected to be a trio with quite the development, and if everything goes well, it will be flashy, dynamic and on time. :)
EDIT: Old video no longer available. Makeover here.