I checked the video out and am still unsure - does it simply save a video with an audio visualization? I thought it would be embedding audio into images somehow, based on the title here.

Exactly that. So, I wanted to send voice messages that I pre-record, and then can send later. The easiest way for my workflow was to be able to access and then send them from my cameral roll, which is pretty much where I store everything that I want to send. So, this records audio, makes a simple wave visualisation, and because its a video file and not purely audio, it can be saved to the photos app ie camera roll vs to files.

I think you have a point, I should make this app's intent clearer.