Nice demo. I especially liked the hair blower trick. 
@kai Do you have/know of of a working example how to play a notification to a Sonos device?
I’m trying to find the proper syntax for the URI for the notificationsound channel.
EDIT: more explicitly: where in my openHAB folder should I put the .mp3 file to have it opened through the Jetty server. I have already tried (without success)
{openhab2home}/extra=> http://localhost:8080/doorbell.mp3{openhab2home}/conf/icons=> http://localhost:8080/icons/doorbell.mp3 and http://localhost:8080/icon/doorbell.mp3{openhab2home}/conf/html=> http://localhost:8080/doorbell.mp3 and http://localhost:8080/html/doorbell.mp3{openhab2home}/runtime/sounds=> http://localhost:8080/sounds/doorbell.mp3
(I could add that to the examples in the OH2 docs for the binding)