So are you surprised that in visiting a site offering keygens that you aren't going to get hit
To give you an idea, just have a look at the number of of-site scripts that would be run, anyone of which could be what avast is complaining about, see image.
So aside from any legal/moral issues of using keygens/cracks to circumvent payment you are at a high risk of infection.
That is plain common sense and I would tend to agree with avast, though with firefox and noscript I don't get an alert on that page (bayi00.blogdetik.com).