Wow, a live TAS, how different O_o. Anyway, in this i am trying to show how to side blj.
if you cant understand me or dont know what mario is doin, here is a hopefully helpful description.
you first must find an angle that is pretty much parallel to the stairs. If you can find a perfectly parallel angle, you can get a great blj, unlike this one, which didnt have a perfect starting angle. ok, once you find the angle, long jump in that direction. now, you need to find an angle where when mario's longjump ends, he lands on a top stair, but then falls down to another. once you find that, you press A the frame before you fall. you continue this process then. you may also notice that marios blj is ending early for some reason. to continue the blj, you must find an angle where when you blj, mario goes up a step and doesnt "air" blj. This usually only works up to a certain point, but if you got a great angle, you dont need to worry about it.
This trick is in most cases TAS only, unless your silentslayers or something ;)