"At the end of a calendar month BetVictor shall calculate all referral commissions, both positive and negative, generated by referrals from the affiliate’s site. As of December 1st 2015, in the event that a revenue share in any calendar month is a negative amount, we shall carry forward and set off any such negative amount against all future revenue commission calculations. For the avoidance of doubt, you will only receive a pay out when there is a positive balance in any given month."

Also looks like they've changed cross-product commission - would have been nice to get an email on the change!