Email chris@gazellia.com and you will get a reply from a person.
The app needs to see a reasonably clear person. Very small figures in a wide shot, heavy backlighting and motion blur all make that harder. A clip where the person fills a good part of the frame works best.
The app will ask which one you want and show you each of them, along with how much of the frame they fill. Someone who is only a small part of a wide shot will not have the detail to read well as a figure.
While a hologram is playing, the controls under the library set the person's height, how far away they stand and where the floor is. Table height is the one that stops them standing on the carpet.
Press Stop under the hologram that is playing. It closes the projection and the sound with it.
On your device, inside the app. Nothing is uploaded and there is no account. Deleting a hologram removes it; deleting the app removes all of them.