The girls in this video are almost all having a bunch of fun - they're (pretty much) all quite obviously amateurs - there's solo / girl-girl / girl-guy sex for, like, three hours and the people who actually shot the video are very good at what they do - an important point because so many videos are ruined by people who have no idea how to shoot porn.
There are very few real 'porn stars' - these days it's just a whole lot of people who have decided they would like to be in a porno - most of whom will never be seen again. But this is not a complaint!
The whole idea of being a 'porn star' has extended even farther into the mainstream of our culture. It would appear that many girls are interested in testing their sexual boundaries and find the whole experience to be less about the money for the session and more about the thrill of adventure and the knowledge that many many people will be finding their own pleasure watching them do so.
Philosophical musings aside, there are several scenes - starting with the first one - which make this a most enjoyable title.