This skip I think works like you go as close as you can(like hugging) to the pen then you kind of go around the pen, so you fall off with down and right held at the same times then when you start to fall down enough, hold up and right and with some practice you should be able to get it. Feel free to take a look at the video in case my writing does not make sense(the video is not a tutorial, it's a video showing the skip). The reason why it may work is because you maybe are not all the way on the ground, but you're not on the platform so it may trick the system to thinking it's a climbable ledge.

(mod edit: there's no such thing as climbable ledges.)