She knows in general what to expect from her adventure but most likely prepared for pretty much anything and accepts everything that is coming her way, and in the process is getting really exciting which is pretty obvious from her facial expressions, sometimes pretty happy ones ;)
When she sticks her butt through the window she is trying to see what comes next and that creates composition similar to the picture on 1 dollar bill ;)
The entire video is 40 min long and full of excitement and action!

This girl is very passionate! Even when she's trying to hide it her passion is getting through her "calm" mask.
The people that she joined were having their fun in progress but weren't too excited about it, this girl brought that spark of emotions that was missing.
The way she kisses, the way she's having sex, even the way she talks gives away how emotional and "ready to have fun" she is.
The entire video is 33 minutes long and full of turns and changes!