I just opened ThinkOrSwim (that I don't use except when looking at historical scenarios which you can do as well), and here is a screenshot showing that if you've spent $750 on 75x 127-strike $0.10 puts on Sept 16 2019 then on Sept 20 2019 you'd end up with $140K by end of the week.
This may be different than what he has done, and I'm not sure of his exact strike and entry/exit points.
View attachment 211629
Here is another scenario showing how someone could've turn $750 into $46K by buying 25x 127-strike puts for $.30 each the day before expiration:
View attachment 211630
Second 1, 25 x 0.30 matches my estimate pretty damn closely.