Andrea, now this is "easy peasy"! Using the example you provided below, all you need is to create a file in a non-Cinelerra directory (so it does not get deleted). For example, I created /tmp/andrea.sh that only contains the one line (it is one line altogether but there is such a thing in linux for a continuation line if it gets too long):

ffmpeg -i "$1" -filter_complex 'extractplanes=y+u+v[y][u][v]' -map '[y]' y.avi -map '[u]' u.avi -map '[v]' v.avi

Also, in your 1 line above, keep in mind that y.avi, u.avi, and v.avi MUST have full pathnames or your output files will end up in whichever directory you are running in. And just as important, you must use "-y" to answer "yes" to overwrite the files or else it will prompt you in the Cinelerra startup window.

Note the "$1" - that is the first argv and in Cinelerra, all you would have to do is go to the Resource window and highlight the "video.avi" file you used in your example and then go to the Shell Cmds icon and click on Andrea instead of Shortcuts, for example. Of course, you have to set up the Andrea command first in Settings-> Preferences, Interface tab "Shell Commands". I updated use of Shell Commands in chapter trouble here locally but have included it below.

I will attempt to make an example.

I was wondering if it was possible to include in ShellCmd some ffmpeg
filters that do not work in CinnGG.

The commands are as follows:

EXTRACTPLANES

ffmpeg -i video.avi -filter_complex 'extractplanes=y+u+v[y][u][v]'
-map '[y]' y.avi -map '[u]' u.avi -map '[v]' v.avi