I'm hearing there were six on the trip, three males, and three females. The male recording this was her best friend...probably gay or bi. That would explain why he was in the room. I'm hearing she was drunk. It appears after the beating, she went back to bed, and died of her injuries, which doesn't sound far fetched, since she was clearly conscious after that girl stopped beating her. Anyway, one of the males claimed he didn't even get to Mexico until after the fight.
It's possible that the one who beat her up, and the one who filmed it, were the only two who really knew what happened, and told the others that she was too drunk to hang, which would explain why they went to the party without her. Then the next morning, those two told the others that she was still out of it. And she might have been, but they didn't want to tell the others what else happened. It appears those two either knew she was dead the next morning, or left her there still drunk and beaten. So whatever they told the others after the fight, they probably believed them, since one of them was her best friend...and they went back home the next day. This may explain why the stories sound different.
At first, I thought it was just her and three girlfriends. If that was the case, then I would still assume they all planned it. But with three men, and three women, I'm not seeing all six of them planning this. I have a feeling she beat this girl over one of those three dudes. By the way, it appears the deceased was a successful entrepreneur, and that's sad. But if what happened to her was out of jealousy, then it was more likely over a man, and not necessarily her success, or because she drove a nice car. That's my take on it so far.