[Milhouse]

If the animated posters/artworks are associated with your movies/tvshows/music then they can be cached by the script, and for the same reason they won't be pruned (cleaned). If they're not being cached and are being pruned then they're missing an association in your media library (in which case you need to give me more details about what it is you're trying to cache - extra fanart and thumbs can be cached by adding cache.extrafanart=yes and cache.extrathumbs=yes to texturecache.cfg).

You can configure the prune process so that it doesn't remove certain files, for example "prune.retain.types = .*\.gif$" would ensure that all GIF artwork is kept in the cache.