Overlay video on top of Animation with transparency

Imagine a Kinect 2 based Unity application that can track a user that come close enought to be tracked and the app can present the user with a skeleton that the user start moving. The skelleton would have a heart in the middle of the upper body.
I want a prerecorded video (with a green background) of a person to show on the side of the user and to kind of rich out to his skelleton and grabs his heart and brings it over in front of the person where he can explain something about the heart using text, talk, audio.
So I want a prerecorded user to interact with an object which can be moved out animation windows and brought in the video screen.
https://ms-studio.net/audiovisual/kinetoscope/