Its a slight of hand. He adds a block to take away while moving them. Count the rows I had to pause it but. They are always 9x7 so the only way to remove a block is to add a block. I'm just not sure when he adds it yet lol
im fairly certain its caused by the different lengths and angles of the bigger
pieces. the first time he moved it around i counted ten in a line. then he bumped
away 4 witch knocked the same line down to 9. then he proceeds to do the
same thing 2 more times always goes up to 10 bumps away 4 rinse and repeat.
nice little trick now do it with parallel cuts.
Angles that are cut with a slight curve not noticeable to the naked eye. They appear to take up more or less room when moved around like he was doing. Each time he rearranged it he was making it slightly larger and was able to remove a block.
That is if I remember correctly. It's been a looong time.