Here it is, Gus' first sentence: "Sit Gus Bottom." It means he wants you to help him sit in a chair or the couch or lately, a bar stool. I took this video a week ago and since then he says it more clearly (although I still don't think anyone would know what he was saying without a translator).
In fact, now he says "I sit Gus Bottom" so it makes a little more sense. He'll say it over and over again until you help him into the chair. It's pretty cute.
And speaking of pretty cute, here is a variation on his sentence: "Shake Gus Bottom." Enjoy!