i don't know how use it with ffmeg but here is command for rtmpdump
Code:
rtmpdump -r "rtmp://50.7.161.36/channels" -a "channels" -f "WIN 11,3,300,265" -W "http://www.hqcast.tv/player/player-licensed.swf" -p "http://www.hqcast.tv/embd.php?live=sabtvhq9_desistreams&vw=600&vh=430&video=0&domain=desistreams.tv" -y "sab" | "C:\Program Files\VideoLAN\VLC\vlc.exe" -
sab tv dekho aur haste raho