You don't see rtmp stream in wireshark because it is not sent to you if you use a new browser.
I had to try a few old browsers to get rtmp stream, and here is good Microsoft..
rtmpdump -r "rtmp://video3.earthcam.com:1935/fecnetwork"
-a "fecnetwork"
-f "WIN 27,0,0,183"
-W "https://www.earthcam.com/swf/streaming/stream_viewer_v3.r31119.swf"
-p "https://www.earthcam.com/usa/newyork/worldtradecenter/?cam=skyline_g"
-y "10874.flv"
-o "2017-11-04_03-51-45_10874.flv"