simpleScreenRecorder
Linux users can use SimpleScreenRecorder, specify a 1280or1024x720 area of desktop to record, place your webcam output (gucview, vlc) in that frame along with other elements, select output profile YT stream, rtmp is then the output, enter in stream url. pick video (vp8 vp9, h264, h265) & audio (vorbis, mp3, aac) . start preview to check if everything is working, when ready hit RECORD. SSR will all pre encode that area of the screen and send it to the stream URL, there it gets rebroadcast to viewers