with this fb1 setup there are actually 5 frames where you can zip.
i hold right, then pause once i hit the flat surface (5 frames work) and hold left until i pause again. i use a visual cue on the bottom right to know what frame i'm on
frame let go of right
1 2nd frame you see a red block - top (14 frames)
2 see the dot on the left of it side (1 frame)
3 the bottom of the dot on the left bottom (5 frames)
4 space under the dot bottom ramp (4 frames) top ramp (2 frames)
5 white line to the right top ramp (8 frames)
in this i got "the bottom of the dot on the left" there is one frame that doesn't work in between the 5 so i pause to make sure
this fb2 strat isn't nearly as solid as fb1. i three tap jump and watch the floor for when to pause. i aim for left of the window on the piston, there are 6 frames that can work. i hold right until the bottom of the window 1:19 then go neutral. the problem is i actually aim for one frame earlier that what i got here, so i can't perfectly predict what frame, i can take a really good guess though, so i am hoping the more i do this as random as it is, i will eventually get a better understanding of it. when paused on the launch frame, i hold down and CBA as i let go. this is just like the roll jump in LR1 where you hold down for 2 frames and jump on the 2nd frame, but you can CBA because you are jumping as soon as you land rather than already being on the ground. you can adjust what the correct frame to launch based off of where you jump, your jump height, and adjust the frame from being late/early when you let go of right to being earlier/later from the launch frame, but the problem is i can't find a way to get the same running speed.
As of today, any new submissions of S3K from the Steam version will no longer be allowed. This is due to a couple of factors but mostly being inhibited availability as SEGA delisted it when releasing Origins. Any existing runs will remain unaffected.