Add to a MailChimp Category?

Is it possible to have this plugin add a category tic for the source of the person in MailChimp?

For example I want to have a page with a hidden video on it and send only people from my Facebook groups to it, then when they signup, they get the tag of “Facebook Group” added to their profile in MailChimp. Then a seperate page for YouTube viewers.

Or would the custom fields work better and have a drop down for them to select where they came from? (Would that then get pushed to MailChimp?)
Thanks, Karissa