While I'm not exactly sure how the implementation of this would look. My main concern with the concept is that it shares the same issue that a lot of location-based services have.

They create interesting new opportunities for interaction - but they aren't solving a specific ongoing need the person has.

For example, in the video you mentioned people aren't very interested in small talk - but is it a problem they are looking to solve?

It's important for people to be motivated to seek out your app and most importantly use it.