Doesn't Springsteen give Frederici an introduction as having been taken from Lawrence Welk during the lead in to Wild Billy's Circus Story? That sure makes it seem like Frederici is there. Very interesting to hear such an early version of that track - a lot sparser than the one ultimately recorded on the second lp.
I also cracked up at the "avante garde" bit in "Thundercrack" - I've heard a couple different bootleg versions of that song but never heard that bit.
I love those early Springsteen shows - there are so many cool surprises in unreleased songs and different cover versions. I used to have a lot of Springsteen bootleg lps which I long ago swapped, and I'm dying to hear things like "Pretty Flamingo" or "Goin Back" again. Hopefully the Vault will find some tapes with those tracks on them.