On MacOS,I tried to stream from the Web Cam using the GUI. Picking up the "isight" and setting the transcoding options, it all worked.
Then I tried to do it from the command line, something like this:
/Applications/VLC.app/Contents/MacOS/VLC qtcapture:// --sout=#transcode{vcodec=mp1v,vb=800,fps=25,scale=1,acodec=none}:udp{mux=ts,dst=host:1234}
And it does not start and the error message is:
main stream output error: stream chain failed for `transcodeacodec=none:udpdst=host:1234}