The problem is simple the "&" sign in your url. You can debug such things when you start vlc like "vlx.exe -vvv rtps:/your-url".
This should work:
"C:\Program Files\VideoLAN\VLC\vlc.exe" "rtsp:/admin:
[email protected]/cam/realmonitor?channel=1&subtype=0" --fullscreen --no-video-title-show...