Well that was something cool. I never expected a bass with overdrive/distortion would sound that groovy.
Just exposing my ignorance. Is a Jam band basically like pure improvisation with no pre-conceived ideas of what you are going to play. Or is there some structure that you are improvising around like jazz?
I think that generally jam bands include improvisation, whether within a song or in between and linking songs. The Grateful Dead were masters and maybe even archetypes, though I think one could look earlier to the Paul Butterfield Blues Band and Cream. The Dead probably took it furthest out to near Free Jazz territory sometimes, as cozmic_cowboy mentioned.
This band I've been playing with is very improvisational - we almost never say anything before playing, we just start playing and find our way. But I wouldn't call it "pure improvisation" - I'm not convinced the drummer is really listening deeper than the general mood, we often follow him - in fact, it's almost like we are playing so that the drummer can play! But it's fun and open and we do listen and react to each other. At this point there are no plans to play out - the drummer doesn't want to, I think mainly because he doesn't want to have to move his drums - which is partly why I got the 360 degree camera that you see in the most recent video, so that I can document the music beyond just audio.