Original: Concentrating on the first order rocking motion, the V6 can be assumed to consist of two separate straight-3 where counterweights on the crankshaft and a counter rotating balancer shaft compensate the first order rocking motion.
Simplified: The V6 has an end-to-end rocking motion. Counterweights on the crankshaft and a counter rotating balancer shaft compensate for some of the rocking motion.