whoa, that must have taken tons of training, nice job bro

Hehe, thanks. :)

As we discussed in IRC, (and as I'll explain now in case anyone else was curious) Nullpomino 7.4 (maybe 7.3?) has a feature to show the pieces in the well in any invisible mode. When watching a replay, pressing the game key F will toggle this feature on or off. Since the replay I wanted to record was from an older version of Nullpomino that desynced with the new randomizer code, I had to do some other fiddling to show the playfield.

I don't know, practice mostly.  I had a lot of fun running TGM2's invisible credit roll in trainers way back when. I think it is best to go in with a pretty good working knowledge of 20G and then just start doing Phantom Mania and TGM M-Roll trainer programs. Being able to handle 20G should leave you at a point in your understanding of the game that lends itself well to approximating the stack surface. From there, you can further develop your stacking style and such as it relates to "playing in the dark."

You made that look easy.

How do you do the alternate [visible] replay, btw?

How do you do this invisibe crap? I just can't do it.