I wonder if it is just good game mechanics or the way that guy processes things in his brain but he always gets tetris on the right side and not the left.
In tetris, only the l and the o pieces spawn exactly in the center. All the other pieces spawn slightly to the left. Therefore, on average, you need to make slightly less moves if you stack on the left side than if you stack right.
First: In Tetris nuking 4 rows at once gives you a greater score than nuking 1 row 4 times. (Same goes for 2 and 3 rows). As the guy learned the game he would have gone for optimizing his score rather than number of lines nuked. As he got better the habit would have stuck even though it wasn't strictly necessary to play it that way. The way to nuke 4 rows at once is to build up everything in 4 or more rows minus the slot that a 4x1 can fit into vertically (the longest piece in Tetris).
Second: Leaving a gap on the right or left rather than somewhere in the middle is the easiest way to accomplish this. If you can't see that, I'm sorry for you.
-1 ?! The "I'm sorry for you" was meant to be humorous, not snarky or condescending. Honestly, sorry about that. Short answer - he just chose the right-hand side arbitrarily is my guess, it has nothing to do with game mechanics. Wasn't meant to be a snark, seriously I'm not like that! :)
