They had singers streaming in live, playing their guitars, singing Grateful Dead and what ever else they wanted to us. The concert went on for 6 hours then an after party.
The highlight was a performance from one of the singers, lovesmiley Gumshoe. He has to be a professional singer. He was awesome.
For a second set he did an acoustic version of The Wall. He first set he did a lot of Ween songs.
I would think that The Wall would be hard to do acoustically but he hit it on the head. It was awesome.