Mecha Ritz Steel Rondo clear bonus- HOW does it work?

[blossom]

OK, there's a replay of 18 million uploaded to YouTube. This is a uniquely confusing video. After the TLB dies and the stage clear bonuses are added up, the player's score is 9,292,790. Then, out of nowhere, that score is doubled exactly up to 18,585,580 and my question is why? I've looked at multiple other videos for Mecha Ritz: Steel Rondo and none of them have this generous score doubling. I've tried to think of why this might be - using all B stages? There are other runs that use all B stages. Not dying? This guy dies a couple times to the TLB. Total rank? Possibly, but 2466 seems to be an insignificant number to celebrate. I think the most solid guess is this score doubling rewards the player for a starting rank of 500, because I don't see another replay that starts with 500. That is pure conjecture, though, does anyone have a clue what's going on here?

[Shepardus]

The original Mecha Ritz had a multiplier based on max rank and total time, which you can see here. Maybe this works similarly, perhaps with total rank instead of max rank since that's what's displayed on the screen just before the final score.