The scam gets more obvious. It's not possible to pay 0.1 BTC through Paypal, Paypal doesn't support Bitcoin transfers.

This is how I suspect this is going to end:
-You either lure in enough new users through this "offer" to get enough traffic, which makes it worth it for advertisers, after which you can pay your Mods
-You don't get new users, you can't afford to pay for Mods, and nobody gets paid.
The latter is what I expect to happen.

There's nothing to lose for you, while many people are wasting their time chasing a position at an empty forum.