Hi, thanks for bringing that up. I went ahead and tested a few other possible games.
I used these solutions as the basis:
https://www.youtube.com/watch?v=6ehiWOSp_wk
http://reversi-nxn.blogspot.com/2008/08/shortest-reversi-game-on-boards-7x7-and.html
For each of these I also tried the same solutions rotated each of four ways (i.e. the same games but starting with each of the possible first moves of black). For the above two solutions they eventually broke down when the AI refused to do the next possible move.
I also tried rotating the game played in my current TAS. Note that in addition to four possible opening moves, on my next turn I have the option of two moves that are mirror images of each other so there are 8 possible iterations to try. Of these 7 additional iterations I was only able to get the AI to make the necessary moves in 2 of them, and those 2 games were slower than my current TAS. One of them was only 4 frames slower though, so it seems very promising that there is an improvement possible.
I'll keep researching this with more possible solutions. I can't find a complete list of shortest Othello games but presumably the total count of 57 possibilities includes rotated/flipped forms of the same games.