Does she seem ok in this scene or is it a bit uncomfortable to watch?
She seemed fine to me. The only weird thing in that scene was the inconsistent use of condoms.
I've seen her anal try-out scene on some porn parody site and that was her being really uncomfortable with what she was doing. There was nothing erotic about it and it was either awkward or funny to watch depending on how you view the situation. Don't forget that these ladies are actors! Bad actors, but still actors. Don't be that guy who gets fooled into thinking these are good girls who are just trying to pay their way through college or some such nonsense and becomes a "Captain-Save-A-Ho." They are after your money and are willing to do more than the average person to get it. You already know if you are type of guy who is uncomfortable with that.
You should still be respectful as you would any other person, but don't over-think it!
Anyway, thanks to the above posters for the uploads!
You can watch the scene I referred to here,
http://efukt.com/21201_Porn_Newbz_Anal_Fail.html