When people dance to these, they have to choose a waltz step or a pivot (or polka) step depending on whether the next bar is a 2/4 bar or a 3/4 bar. Trouble is, you don’t know in advance, which makes for hilarity. For dancing, we’d play this a lot slower.
This dance form has been around since the middle ages. Here’s more information on zwiefachers…
Alte Khate
I play fiddle, concertina, piano, viola, and sometimes viola with two bands in central North Carolina, near RDU and the Research Triangle (actually closer to Chapel Hill and Hillsborough than Durham, but anyway, central). You can see these two wedding ensembles at our site 
