using ffmpeg to make mirror image video
ffmpeg -i originalvideo.MOV -vf "crop=iw/2:ih:0:0,split[left][tmp];[tmp]hflip[right];[left][right] hstack" output.MOV
the above command was taken from https://trac.ffmpeg.org/wiki/FancyFil...
I slightly changed the command so that I could get an output file. I had a .MOV file so my output file was .MOV but you will probably want to use the same file type as your original file.
I got the link to the ffmpeg website from looking at a video on the mandlebrot filter effect that I might try out too. The link is below:
• FFmpeg Mandelbrot Filter Effect