I know there is the command line:
vlc.exe --logo-file="icon.png"
This only sets the path to the logo but doesn't activate it. So I'm looking for the command line that shows that logo, too.
You're close. But you also have to tell VLC that you want to display the logo.
For local playback you can do this:
vlc --sub-filter logo --logo-file icon.png video.avi
If you want to stream the video you have to use the transcode
directive:
vlc --logo-file icon.png video.avi --sout "#transcode{vcodec=...,vb=...,sfilter=logo}:std{...}"
Check out the VLC wiki page on how to add logo? for more examples.