FFmpeg: The recursive effects of stacking tblend filters

# Twelve stacked 'tblend=all_mode=difference128' filters.
# Deblocking 'spp' and 'average' filters used to mimimise strobing effects.
# Due to latency issues, the result in ffplay will differ from a ffmpeg rendering.

ffplay \
   -i video.mp4 \
   -vf \
   "
      scale=-2:720,
      tblend=all_mode=difference128,
      tblend=all_mode=difference128,
      tblend=all_mode=difference128,
      spp=4:10,
      tblend=all_mode=average,
      tblend=all_mode=difference128,
      tblend=all_mode=difference128,
      tblend=all_mode=difference128,
      spp=4:10,
      tblend=all_mode=average,
      tblend=all_mode=difference128,
      tblend=all_mode=difference128,
      tblend=all_mode=difference128,
      spp=4:10,
      tblend=all_mode=average,
      tblend=all_mode=difference128,
      tblend=all_mode=difference128,
      tblend=all_mode=difference128 
   "

In the video above, 4 versions of the effect are shown. In order:
- The effects of the tblend filter chain as given
- A tblend fliter chain four-times as long
- The 'mode' alternates between 'difference128' and 'difference'
- A 'average' mode between each 'difference128' tblend filter


Here, the result of the shown tblend filter chain is combined with the original video, using various modes. In order:
- all_mode=difference128
- all_mode=difference
- all_mode=multiply128
- all_mode=multiply
- c0_mode=difference128
- unknown 'average_test.mkv'
- unknown 'all_average_test.mkv'
- unknown 'difference_test.mkv'
- unknown 'difference128_test.mkv'
- Original source material

source video: https://www.youtube.com/watch?v=50lAMbJUXfc