Make a seamless looping video from a normal video (colab)

colab_looping_video.py

# assume you have out.mp4 that is a normal video

!ffmpeg -y -r 30 -i out.mp4 -vf reverse reversed.mp4
!ffmpeg -y -i out.mp4 -i reversed.mp4 -filter_complex "concat=n=2:v=1:a=0" output.mp4

print('\nSeamless loop (original saved to out.mp4):')
show_video('output.mp4')

If you want to flex and do everything one line:
!ffmpeg -y -r 30 -i 'out_%*.png' -lavfi "split[x][y];[y]reverse[z];[x][z]concat" -crf 15 -preset veryslow -pix_fmt yuv420p out.mp4