I don't think HTMLgoodies maintains their own additional copyright over user-submitted content. It is my understanding that each participating user provides their own copyright statement within the code uploaded.
Yes they do ....
99% of the time they say "Feel free to use this code so long as credit notes are left in." and then they state whether they allow corporate use or not.
If you're going to use it for a business, contact the author and agree on an amount to pay them, usually a few dollars.