Snuffy and Dr Price, this is what I hear Rees Baldwin singing:

            You're (or "You are") nothin' but a humbug,
               So dey say, so dey say!
            You're (or "You are") nothin' but a humbug,
               Dat's all I know!

            Catfish growin' on a huckleberry vine....

            Dandy Jim from South Carolina....

            I'se come (or "Ask him") up to marry Dinah....

The differences of interpretation here are minor. I feel quite certain about Baldwin's "minstrel-show" pronunciation of "dey" and "Dat's." Therefore I prefer "I'se come" to "Ask him," though either is possible.

Baldwin's rendition is very spirited.