You can also watch Paul Ponna's demo...
Avatar Builder Pros & Cons
The 3D characters are great for adding Brolls to your live action videos, or for creating an entire video itself. However, I hope they will add a video render preview plus speed up the render time.
Avatar Builder can be a useful app but in case you're looking for other alternatives, here are my recommendations...
And if you're looking for a full-pledge primary video editing app for creating longer form videos, I highly recommend Filmora.
My special BONUS for you if you grab Avatar Builder from this page...
A collection of professional 3D elements in different categories.