ffmpeg -f lavfi -i "color=r=60:c=black:s=1600x1200:d=120" \
-itsoffset -22.5 -i coil.webm \
-itsoffset -15 -i coil.webm \
-itsoffset -7.5 -i coil.webm \
-itsoffset 0 -i coil.webm \
-t 120 -vsync 0 -c:v libx264 -crf 20 -preset ultrafast -an \
-filter_complex "\
[1:v]loop=3:1800:0[tmp1];
[2:v]transpose=1,loop=3:1800:0[tmp2];
[3:v]transpose=1,transpose=1,loop=3:1800:0[tmp3];
[4:v]transpose=2,loop=3:1800:0[tmp4];
[0:v][tmp1]overlay=x=480:y=720[corner1];
[corner1][tmp2]overlay=x=1120:y=280[corner2];
[corner2][tmp3]overlay=x=480:y=0[corner3];
[corner3][tmp4]overlay=x=0:y=280" output.mp4