Here's your answer
I got an offer also, $300. Probably just a general promotional run here at year end.
Edit: Seeing as how the question asked is from an expert member, I assume they already know everything I posted below, hence I misunderstood the question (presumably regarding FTP vs. bonus cash release). I'll still leave it here in case it helps newer FT users. My mistake, I think.
As you play in (cash) ring games or tournaments, you accumulate points. It's a specified amount of points on tournments depending on how high the dollar amount buyin was. On ring game, the higher the pots played, the more points you accumulate. As you accumulate points, your $100 bonus is "slow released" to you. Depending on how much your initial depopsit (and ONLY your initial deposit was) you may get $2.00/$5.00/$10.00, etc. released into your bonus account every so often, until it reaches the maximum of $100.00. It's shady wording to trick you in, but if you play well, you'll eventually get your entire $100 bonus given to you.
You can always check your bonus account under the Cashier's section to see your bonus meter/how much you've earned/how much longer to go until your next release, etc.
I "think" this answers your question but I could be way off base. If so, my apologies.