Jerry is on fire throughout this show. This was one of the '81 shows I was thinking of when singing the praises of the year on a different thread.
I have to admit that whatever Brent was doing in this Minglewood, along with that effect, had a particularly nasty way about it that came close to rivaling some of Jerry's nastiness.
So, in conclusion

I'm not so sure I feel Jerry blew Brent (Bobby, definitely) out of the water. More like Jerry had the upper hand and could be seen holding Brents head under water and toyed with him, occasionally letting him up for air. Bobby, on the other hand could be seen off in the distance in the boat, keeping Jerry and Brents drinks sufficiently chilled.

Now you Bobby fans relax. I'm just funnin.