not dissing but you can really see the flex in that frame during the first section - its going from side to side.
Yes, the frame flex a little in the asfaltic Sprint section of the movie. But the cam oscillates a little bit too.. But, honestly, I don't think that the flex is a problem, the rear triangle is tight, I don't see any mechanical problem, it's all ok.. But if I grab the seat, and pull the wheel to the side with my foot, the wheel and the triangle bends a little...So, the material it is not 100% rigid !! It has to flex! Cannondale Scapel don't have a pivot, it bends the chainsteel (I mean, the down tube of rear triangle, not sure of it's name)..
And remember, in sprint, we apply a lot of lateral forces, that have to be dissipated... How? With tires bending, and frame bending (bending=flexing, isn't it?).