Ok, lots of questions on the new bonus - I have answers!
The bonus is granted on Free BTC rolls. To be eligible for the bonus you need to participate in some Multiply BTC rolls and/or buy lottery tickets. On your Free BTC screen (sample below) you'll see what your progression % is toward achieve bonus eligibility and the amount of satoshi the bonus is worth. In the sample below this user is 9+% toward achieving the bonus, once that number gets to 100% they can claim the bonus on their next Free BTC roll.
The size of the bonus ranges from the base Free BTC roll to 19x that number (also shown as the higher number on the screenshot below). The more you achieve the bonus the greater your chances are of getting a higher payout.
Anyone achieve 100% yet? Let's see some screenshots!
Thanks to favdesu for letting us borrow your screenshot here!

I don't understand this message... could someone explain please?