As he continued with his remarks, Biden was yelling. "It says, 'I'm an American! I'm an American! That's who I am.' To a smattering of applause, Biden continued, insisting, "I'm serious about this! I'm not joking! And folks, our politics, as I've said, has become so divided," he continued, bringing it back to that original point in the clip. His remarks came off as redundant, as he continued to speak about "wear[ing] the uniform of the United States of America," and, just as he's done in the past, when president, talked about America being founded "on an idea."
However, as Biden went on to reference the Declaration of Independence, he couldn't get the words out to finish saying "pursuit of happiness," and the phrase just sort of ended with him slurring his words.