ffmpeg invalid argument. Which argument was invalid? UPDATED with info from -report

I'm new to ffmpeg.
I am trying to loop a video to a linux v4l2 device.
ffmpeg -stream_loop -1 -re -f lavfi  -i &quot;movie=snail.mp4&quot; -f v4l2 /dev/video4 -report

It plays the video once and then exits with the message &quot;Invalid
[Parsed_movie_0 @ 0x56289dec9a00] EOF timestamp not reliable=N/A speed=   1x    
Error while filtering: Invalid argument
frame=  391 fps= 25 q=-0.0 Lsize=N/A time=00:00:15.64 bitrate=N/A speed=0.999x    
video:43988kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown

Which argument is invalid and why?
The output of the report file generated by ffmpeg is available here: https://gist.github.com/ahoffer/7217aa0572061e7c255cf08914be53e2
-stream_loop is buggy in versions older than 4.1, so upgrade.
Also, stream_loop won't work with movies opened via movie filter. Use it as a direct input.
ffmpeg -stream_loop -1 -re -i &quot;snail.mp4&quot; -f v4l2 /dev/video4 -report