The most consistent way to do it is by - stopping in the air for a little bit so you don't hit the fire and not getting your speed caught, and then throwing the axe as high as possible on the wall without it flying over it. This strat is very unique as if throw the axe one pixel higher it goes just above the wall and flies through the fire, killing you and losing a few seconds. If you go one pixel lower then you don't die and the run continues, only missing out on the 0.4 second save. I highly recommend not going for this in runs, stop in the air like the video does and try to aim 3-5 pixels lower than what you need to get fast fall, and sometimes you might actually get lucky in a run but there are many more time saves not nearly as difficult as this one.

Video of the fast fall -