If you want to learn how a move works you should approach it more analytically.
First lets not call this turnover bc as shown in the Knowledge Base, a turnover requires the use of one free arm posting off the floor. So this is a throw, and more specifically we call this sacrifice throw.
Sacrifice throws require you to forfeit your base and COG to establish a momentum that you want to transfer to your opponent.
In this replay you see both fighters open in the same direction except that SPCR's tori drops is COG lower relative to that of his opponent's COG. Both these elements are crucial to starting this move.
Imagine the opponent by chance opened in the opposite direction as SPCR he would be able to sprawl his foot-base and then force SPCR into the floor, as Iskenos pointed out.
But because the opponent over extended his base and thus lost his footing, SPCR was able to establish the rotational momentum.
By kicking off the floor, SPCR was then able to transfer the rotational momentum into his opponent.
I would also attribute the speedy victory to the opponent's failure to counter raise his arms.