Issues looping a stream with FFMpeg
Try with the movie filter instead

ffmpeg -loop 1 -i image.jpg -filter_complex \
        "movie=video.mov:loop=999,setpts=N/(FRAME_RATE*TB)[1v]; \
        [0:v][1v]overlay=x=main_w*0.44:y=main_h*0.33[out]" \
       -map [out] -t 00:00:15  out.mp4