Hello Pascal,
I am also trying to publish a WebRTC stream and consume it from RTMP endpoint.
I went through the tutorial you linked but was unable to play the stream from the rtmp endpoint. I tried the following endpoints in VLC from the network stream playback option:
rtmp://localhost/WebRTCApp/stream1 live=1
rtmp://localhost/WebRTCApp/stream1?live=1
rtmp://localhost/WebRTCApp/stream1/live=1
I am using the community edition. Perhaps the tutorial is outdated or enterprise edition is required?