Fake fucking is for the most part, understandable, if the actors is straight as bottoming can be difficult and for some perhaps emasculating. However, pretending to give head to a dildo while instructing a gay couple while being serviced by a gay man just screams ridiculous. Lean forward or get out of gay porn!
Basically, if you want to download the video on your hard drive, you need to choose the credit option, which will cost you around 5 to 10 credits for one scene. Otherwise, you'll be streaming the videos you watch.
Personally, I prefer a fixed monthly membership price and choose the scenes to download on my hard and not be worried that I am exceeding my allotted credits.