PLEASE HELP ME!! What movie is this from??

The other night I was watching TCM and there was a black and white movie short or possibly a scene from a movie that featured a band of hillbillies playing instruments on a stage. One of the hillbillies was the typical goofy hillbilly fool and he looked very much like Harpo Marx, but it was not Harpo Marx. I believe he was playing the standup bass or a banjo and as he played his leg kept jumping. He used his leg to keep the rhythm and occassionally had to catch it to stop it from going out of control. I thought it was absolutely hilarious and I'd like to find out who the actors were or what movie featured them. Does anyone have any idea what I'm talking about?? I really need someone to help me find out what movie this is. IT'S DRIVING ME CRAZY!!!!!!