u uisng localhost without port number adding at the end of it. when u dont specify post by deafult it mean :
localhost:80
and local tunnel hide that 80 port by assigning it to a public ip only for http protocol based stuffs.
that click button hosted in ahttp server written in cirrus.js of signaling server.
but the webrtc video that also produced by cirrus.js using webrtc prtotocl . not https.
hence the play button works only. but not the video.
to make video working u need a turn server hosted somewhere but definatly not in local host which is connected to a router