We investigate the zero-magnetic-field dynamic scaling in ${\mathrm{Bi}}_{2}{\mathrm{Sr}}_{2}{\mathrm{CaCu}}_{2}{\mathrm{O}}_{8}$ thin films from nonlinear current-voltage $(I\text{\ensuremath{-}}V)$ characteristics and by using the concavity criterion recently proposed by Strachan et al. [Phys. Rev. Lett. 87, 067007 (2001)]. We find that fresh samples show a BKT-like transition with $z=0.8$, smaller than expected for a conventional Berezinskii-Kosterlitz-Thouless transition. The effect of sample size and finite Josephson coupling are discussed. We examine the effect of thermally-induced disorder in the oxygen sublattice finding that the BKT-like transition is suppressed by point disorder.