He actually has (I would have to assume) between 9 and 11 negative levels in that screenshot. Not 7 (as you previously mentioned).
12 Barb has a base +4 Will (2 Ftr has base 0), he shows a +0 for Wisdom, so:
4 (base) - 18 (9 neg levels) = -14
4 (base) + 2 (resistance) - 20 (10 neg levels) = -14
4 (base) + 4 (resistance) - 22 (11 neg levels) = -14