Agree with Ghilly on the popcorn advice. I've always given my dogs popcorn when we are eating it but not a lot of it. As a matter of fact, I taught a few of my dogs to catch using popcorn as it won't hurt them if/when it hits them in the face. LOL
PLAIN popcorn without butter and salt is an OK snack for dogs, IN MODERATION. A couple of pieces throughout the day as a snack won't hurt him in the least. You don't want to give him popcorn with all the trimmings, though, as it will eventually make him fat, just like it does to us! :)
Ghilly