Change display aspect ratio is misleading

Hey, as discovered at the Tate workshops, the change display aspect ratio recipe (that i wrote)is misleading,as it also transcodes to prores.As stream copy doesn't work with a filter, specifying a codec is required .
@dericed wrote a better one in his 'change stream properties' script,which uses field_order,but from my limited tests, this doesn't work with Matroska,only mov(probably mp4 too?).

I think the setfield script should stay in but a better explanation is required so that the re-encode is made more obvious.