This site does not only offer "free" movies and TV shows, but is also an illegal streaming service, like the former infamous kino.to, which is now under investigation. The providers are incarcerated and some avid users have surely also been investigated.
I'd keep my hand off of it, if I were you!!
Generally speaking, it is nearly impossible to get malicious software installed without giving it permission by entering your password.
In that aspect, OS X works inherently differently than Windows. It has no registry that can get infested and far stricter permissions that apps have to deal with.
However, bad cookies, malicious flash files and other stuff can do stuff to your browser that you want to prevent by reviewing and adapting your browser settings to your needs!