FFmpeg add logo watermark to live stream
Use the overlay video filter:

find "/video path" -name "*.mp4" | xargs -I $ "/ffmpeg path" -y -re -i $ -i watermark.png -filter_complex overlay -c:a copy -f flv rtmp://xxx.xxx.xx/live/


You can't filter video (-filter_complex or -vf) and stream copy (-vcodec copy) the same stream. If you try you'll get an error:


  Streamcopy requested for output stream 0:0, which is fed from a
  complex filtergraph. Filtering and streamcopy cannot be used together


So remove -vcodec copy when filtering the video.