Annamill....the dead did play quite a few trad songs....and adapted them at times to make it their own....they have recorded versions of Staggerlee...and Samson and Delilah....and many other songs...

At the one show I got to see they did Pretty Peggy-O....

there are also a few albums out with Jerry Garcia and David Grisman... thanks for letting me know about this film....will have to check it out!