That was retail price. Most the operational aspects at google are somewhat fixed costs.
Power Cooling are per Server. However given the low load on longtail video content & ability for google to co-mingle high IOPs workloads with low IOPs workload.
Its not that simple...
TLDR, storage is fairly cheap in scheme of things. Even if having infinite video storage costs 100mil/year, google likely makes more from content monitization.