It is sort of doing what you want... you dont have to show the first two cats. And i still think you can do it with a custom search...
But
Make a cat "movie.filter.results", this can be hidden and point its details to "movie.filter.results.details", set it to instant update.
Make another cat "movie.filter.results.details", this is the cat you show on the screen (it will contain the movies).
trigger "set filter:movies:genre:movie.filter.results"
You now need a pluging to let you move to a given entry in In "movie.filter.results" (find display = "animation"). You could use xJumpTo (a plugin i wrote ages ago) to do this.
You will now have a cat ("movie.filter.results.details") whichs looks like a normal movie cat when you have filtered on genre and then drilled into animation(but the user has not had to do anything).
Sean.