A complete time-resolved x-ray imaging experiment of laser heated solid-density hydrogen clusters is modeled by microscopic particle-in-cell simulations that account self-consistently for the microscopic cluster dynamics and electromagnetic wave evolution. A technique is developed to retrieve the anisotropic nanoplasma expansion from the elastic and inelastic x-ray scattering data. Our method takes advantage of the self-similar evolution of the nanoplasma density and enables us to make movies of ultrafast nanoplasma dynamics from pump-probe x-ray imaging experiments.