It is free as long as your bill is under $50,which is very uncommon. My most recent bills were under 1$,with some big wikis. So, unless you plan to have very high traffic it should have no cost.
I don't like pictures encoded as base 64. I like when I can put image to folder, and write (get) path to this image. In TW5 it has name _canonical_uri something like this https://design4shop.ru/heeg.html#luhta_img9I think that idea with DBaaS will make TW5 the best CMS for small sites. But it will be great to add files upload to server system, not to encode them to base 64.
And what about security? Can somebody hack my base properties and make a great traffic to my cloudant account?
You don't put any login and password in your video.