I still haven't found a full stage breakdown for this festival, but master artist lists for the festival are online. There are some impressive names: David Bowie, Lou Reed, Patti Smith, Nick Cave.
Beck's performed on the middle of the three days, and I included the full Saturday lineup in the list below.
Beck, in 2013, in a remembrance of Lou Reed who had just died, mentioned: ""I remember around '95, we had just played a festival, and he was right after us, so I was coming offstage when he was going on. I wanted to introduce myself, but I wasn't confident enough. So I never got to meet him. I'm really sad about that. The truth is, I haven't even had time to digest the news that he's gone. Man, what a loss."
This is the only festival I have in the database with Lou Reed at it, so I assume this was the night of Beck's story. (Update: I've since discovered a couple of others with Lou, but still imagine this was probably the show.)
[people and bands
Bass: Justin Meldal-Johnsen
Drums: Joey Waronker
Guitar: Beck Hansen
Guitar (Electric): Smokey Hormel
Headliner: David Bowie, Lou Reed, Red Hot Chili Peppers
Keyboard / Synthesizer: Theo Mondle
Other Band: Ash, Frank Black, Ministry, Miossec, Nick Cave, Patti Smith, Red Cardell, Theo Hakola, Trashcan Juice, Ultra Orange
Vocals: Beck Hansen