UPDATE: Fast Version with Full segment video + Inputs Guide

TIMER & APPROACH

there are 2 very important things to keep in mind for this "NecroMineSkip" strat to work: 1) the dead body slides towards the right at a certain speed, so it takes a fixed amount of time before it falls off into the void... 2) we instantly zip to the body if we are in a certain range close to it, so we need to keep a safe distance up until the last moment... with this in mind, for things to go in our favor, we need very reliable and consistent strategies for timing and approach:

• we have to start a timer at the exact moment when we zip back to the body and start dragging it right [4.3] ... if you can't start a new timer or pay attention at an already running one (like the speedrun timer itself for ex) there are other ways to solve this problem ... the elevator movement is very reliable and can be used to our advantage : if we zip back to the elevator [4.5] before it stops at mid level (so it keeps going smooth all the way up) it takes exactly 10 sec up, so we can use the moment when the elevator opens at the top level as a 10 sec marker since we started dragging the body right.
• at the top level, we need a reliable approach that always takes the same amount of time to reach the critical point on the right. the method presented in the guide is a simple way you can have an uninterrupted and reliable approach that can always work out the same way... plus it offers a couple of adjustment points in case you need to slow down or speed up your approach

IMPORTANT NOTE : I didn't have room to explain the last step properly ... the reason you have to switch direction (tap left) before you release the body is because that way you instantly let go of the body, as opposed to just releasing grab, which has a very long animation of the kid laying down the body and then walking off ... so a quick tap in the opposite direction where you pull -then releasing grab- is the fastest way to let go of the body and instantly be free (to fall safely on the other side of the door) ...