I'm halfway into the video and it seems like an impressive use of half a million lines of code. The developer(s) is a UV artist himself and says the algorithm's process is close to how he would do things himself. He discusses the entire algorithm but it comes down to identifying different features like hard flattish surfaces, cones, strips, smooth surfaces, etc and handling them independently.
It's probably not open source. It says email Quel Solaar for licensing. He is targeting game studios before moving on to film vfx studios.