[side note] I actually beat that score two days ago.

[/side note]
It's all about chance (what some call luck). It's pure chance to get a game where they give that many combinations, and it's pure chance that I have a good game at that
same time. For instance, the game from my video
could have been a 9000 point game - however, I wasn't on top of my game to get that score.
Another for instance, sometimes I'm on top of my game and, by chance, I'm not given a game that has as many possible points. I've had great games and barely scored 8000, if that - I've also had bad games where I get 8300 points... it's all chance.
Keep up the good games.