If it's the performance i think (youtube won't work for me... i think he knows how much i hate it
), it is on the 1989 03 21 - Leeds, UK DVD that Chris Habib shared on Dime in the past year. At some point was up on Zomb too.
I have also a lossy version from Soulseek , that i think i've uploaded here some time ago, but i can't remember for sure (i have to check it out EDIT:
http://www.sonicyouth.com/gossip/showthread.php?p=332190&highlight=Soundstage#post3 32190).
If there is interest i can help upping it again or seeding the DVD. Just let me know.