Around 1 hour 53 minutes to beat on 2 players, Casual Mode. Just a quick kill with CoolHandMike. He's the second player. I may still get back to my solo veteran playthrough. I was about 1/2 way through.
Stage 6 crashed at the end and had to be redone. So you will see me repeat the stage twice in this video. I left the full playthrough unedited. We were able to improvise alot of bullshit with stacking ontop of eachother to get to shortcuts and hit airborne bosses, etc. Very entertaining game to fuck around with in Co-Op. Nice feature. I havent played in about 15 months so some of the rigid jumping, hovering controls threw me off at parts, but overall the mode is very easy on 2 players but alot of fun.