How do you find the name of actors in commercials?

Is there a website to find this?

I'm not aware of any central database for commercials similar to IMDB.com

The library of congress has a dry collection of commercial producer credits, that may provide a contact point for making inquiries.
www.loc.gov/rr/mopic/findaid/mpfind...

Here's a collection of commercials that might be useful
www.tvaddb.com/home.php