The avoidance of excess or extremes is important,beit food,moisture,temperature ect.

I give leftover popcorn to the crows.
I imagine popcorn to be salty (greasy?) bedding.

He did mention prior to butter or salt application. Sbryce in that case I would give it to the worms and its not likely you are ever going to have so much at one time to cause any imbalance. Popcorn without butter and salt is just a grain and popped should be a nice fluffy treat for them that breaks down readily.

We had some leftover from a movie and I tossed it as it had all the good stuff that makes us want more of it, The Wife was going to feed it to the chickens but really it didnt seem like it would be good for them either.