one of the players jumps on the rails, then jumps on top of a train and then jumps on an invisible wall (your best bet it to aim for umbrella logo and be in the middle of the train), then you run along this wall and jump down to the elevator which must come up after you press a button, then the 2nd player triggers the elevator, you move to a platform and then you jump right below the elevator, aiming for the exit and the second player who's on top must kill himself in order for the first player to continue it is risky for casual/normal speedruns but for professional/veteran it is less risky since if you fail you can suicide
possible fails: if you overshoot the jump on the invisible wall from the train, you'll still get a time save (not as much of course) but at least you won't lose any time at all (UPD: actually I just realised that this kind of time save will work perfectly for solo runs!) if you won't reach the invisible wall, you'll just fall on the train tracks and thats pretty much the end of your run if you're running on low difficulties and cant suicide (BUT if you position yourself like I did on the video, you pretty much can't miss the jump)
in the end this skip saves more than 2 minutes, I'd say it's a must-do on every coop run but of course the downside is that it can't be done in solo runs (unless if you won't go for a jump down to the elevator and just run to the button like I said above)
ok so finally after an hour of testing I concluded that this skip IS doable in solo but not as fast (only around 30 secs slower than in coop but its still faster than usual playthrough by around 2 minutes) no matter how hard you try there's not enough time to reach the lowest floor before the invisible wall kicks in, even if you do it perfectly
@rozukk can you pls remove "coop-only" from the title? :D