I have already warned them about the confusion this term may lead. IMO, it's not a "free" play, but a "bonus" play.


From their FAQ:
For each Free Play you have and want to use, you have to play 0.10 BTC. For instance, if you want to use four Free Plays, you have to bet 0.40 BTC."

As you can see this is not as free as they advise.