Create a video / animation to showcase our product

We have a set of screen recordings for our smartphone app. The app requires the user to interact with the physical world, so we would like to embed the recordings in a simple animation which shows how the two smartphones interact. The final video will contain 12 screens.

Only very basic animation is needed: two smartphones tapping a box and growing / shrinking to show the various videos.

A full step-by-step requirements doc is available.