Is it possible to create an endless loop using concat?
ffmpeg concat demuxer supports nested scripts 
 with the header "ffconcat version 1.0".

Example of endless recursive playlist script "test.txt":

ffconcat version 1.0
file 'video1.mp4'
file 'video2.mp4'
file 'video3.mp4'
file 'test.txt'


ffmpeg command: 

ffmpeg -re -f concat -i ./test.txt  -c copy -f flv rtmp://....


Note: all file paths must be "safe", 
  because the header "concat version 1.0" also resets the safe option to 1.