After another review of the clip, Machida than looks more like he is intending and distinctly doing Aikido. That waza more distinct. But, I am not sure because I don't know his background, can't say for sure. Just speculation.
Shinya Aoki's doing the elbow lock that he could of just fell into and didn't come form any art. There is that possibility. But he does use his hips to make it work. I don't know is background either.
I am sure there are those who know these fighters better than I. I haven't looked into their training background.
Why haven't you checked their background?. Not a difficult task.