The way you use rtmpdump you are not saving the stream, you pipe output to VLC.
I did not succeed in playing the stream with VLC only, you can use streamlink instead of rtmpdump.
Code:
set url="rtmp://video3.earthcam.com:1935/fecnetwork app=fecnetwork swfUrl=https://www.earthcam.com/swf/streaming/stream_viewer_v3.r31119.swf playpath=10874.flv"
streamlink %url% worst
