It is definitely NOT legal, otherwise why would they take stuff down at a company's request? Because they don't want to get sued, that's why. These albums cost money, and so by providing them for free, this site is distributing copyrighted content illegally. It's not the same as somewhere like Rapidshare because this site actively promotes and hosts the files, whereas stuff gets deleted from RS all the time. All the same, it makes no difference to them because the companies that own the music don't usually care enough to do anything about it, since videogame OSTs don't make up a very large portion of their revenue.
And I don't really care either way, I'd dl stuff anyway.