After I see the first frame the OSD player just closes. If the camera is off then I see OSD with black background just fine.
./osd -w 1366
Use: mavlink_port=14551, rtp_port=5600, rtsp_url=none, codec=h264, rtp_jitter=5, osd_render=0, screen_width=1366
GST pipeline: udpsrc port=5600 caps="application/x-rtp,media=(string)video, clock-rate=(int)90000, encoding-name=(string)H264" ! rtpjitterbuffer latency=5 ! rtph264depay ! h264parse config-interval=1 disable-passthrough=true ! avdec_h264 ! glupload ! glcolorconvert ! glvideomixerelement background=black name=osd sink_0::width=1366 sink_0::height=768 sink_1::width=1366 sink_1::height=768 ! glcolorconvert ! gldownload ! autovideosink sync=false videotestsrc pattern=solid-color foreground-color=0x00000000 is-live=true ! video/x-raw,width=640,height=360 ! cairooverlay name=overlay ! glupload ! glcolorconvert ! osd.
gst autovideosink0-actual-sink-xvimage: NULL -> READY
gst autovideosink0: NULL -> READY
gst gldownloadelement0: NULL -> READY
gst glcolorconvertelement1: NULL -> READY
gst osd: NULL -> READY
gst glcolorconvertelement0: NULL -> READY
gst glcolorconvertelement2: NULL -> READY
gst gluploadelement0: NULL -> READY
gst gluploadelement1: NULL -> READY
gst avdec_h264-0: NULL -> READY
gst overlay: NULL -> READY
gst h264parse0: NULL -> READY
gst capsfilter0: NULL -> READY
gst rtph264depay0: NULL -> READY
gst videotestsrc0: NULL -> READY
gst rtpjitterbuffer0: NULL -> READY
gst udpsrc0: NULL -> READY
gst pipeline0: NULL -> READY
gst gldownloadelement0: READY -> PAUSED
gst glcolorconvertelement1: READY -> PAUSED
gst osd: READY -> PAUSED
gst glcolorconvertelement0: READY -> PAUSED
gst glcolorconvertelement2: READY -> PAUSED
gst gluploadelement0: READY -> PAUSED
gst gluploadelement1: READY -> PAUSED
gst avdec_h264-0: READY -> PAUSED
gst overlay: READY -> PAUSED
gst h264parse0: READY -> PAUSED
gst capsfilter0: READY -> PAUSED
gst rtph264depay0: READY -> PAUSED
gst videotestsrc0: READY -> PAUSED
gst rtpjitterbuffer0: READY -> PAUSED
gst udpsrc0: READY -> PAUSED
gst pipeline0: READY -> PAUSED
gst gldownloadelement0: PAUSED -> PLAYING
gst glcolorconvertelement1: PAUSED -> PLAYING
gst osd: PAUSED -> PLAYING
gst glcolorconvertelement0: PAUSED -> PLAYING
gst glcolorconvertelement2: PAUSED -> PLAYING
gst gluploadelement0: PAUSED -> PLAYING
gst gluploadelement1: PAUSED -> PLAYING
gst avdec_h264-0: PAUSED -> PLAYING
gst overlay: PAUSED -> PLAYING
gst h264parse0: PAUSED -> PLAYING
gst capsfilter0: PAUSED -> PLAYING
gst rtph264depay0: PAUSED -> PLAYING
gst videotestsrc0: PAUSED -> PLAYING
gst rtpjitterbuffer0: PAUSED -> PLAYING
gst udpsrc0: PAUSED -> PLAYING
gst autovideosink0-actual-sink-xvimage: READY -> PAUSED
gst autovideosink0: READY -> PAUSED
gst autovideosink0-actual-sink-xvimage: PAUSED -> PLAYING
gst autovideosink0: PAUSED -> PLAYING
gst pipeline0: PAUSED -> PLAYING
gst thread exited