GSP made it look a lot better than your other video (of course he would, he's GSP
).
GSP was also significantly closer most times when he initiated the takedown, making it more effective IMO.
I'd call what he was doing a more of kamikaze double than the video I referred to; his takedown's effectiveness comes from blocking the back of the knees and driving forward rather than the dump. When he dumps rather than driving forward, he more often muscles it (the one where he's against the cage and picks the opponent up). He can do that, he's GSP. That wouldn't work quite so well against a significantly bigger and heavier opponent, like say Brock Lessner. A person not having MMA strength would struggle a bit with his method.
I really liked the kamikaze double when I wrestled. But instead of having my head to the outside, I buried my forehead into my opponent's chest. And I'd pull behind both knees with my forearms. Then again, there was no risk of a punch or knee coming at me in wrestling, so leading with my forehead wasn't a risk.
But is a good video. Shows some good variation on the traditional double-leg.