I'm sure that this is down to me rather than the package, but I followed the instructions in the README and the overlay seems to be working fine, but I don't seem to have a VLC process and don't see the video. I'm on a Pi 2B running Raspbian Buster, the light version.
I have a Pi 3 somewhere so I'm going to shift the SD card over to that and see if it makes a difference.
Sorry I don't have anything more useful to add. I really like the idea behind the app – thanks publishing it.