The present paper investigates two controversial issues related to subjective video quality assessment, namely the relationship between continuous and discrete scale evaluations and the impact of the Gaussian hypothesis in modeling the scores assigned by the human observers. The theoretical background is obtained by reconsidering a non-linear random variable transformation formula established in our previous work and by instantiating it for both Gaussian and non-Gaussian cases. The experimental results are obtained by considering a total of 240 human observers, evaluating both stereoscopic and 2D video quality content, each of which considered at both high quality and low quality (as a priori expressed by objective measures). The results demonstrate that the Gaussian hypothesis cannot be accepted and that the relative error in the mean opinion score estimation can be reduced by 2-4% when considering a non-Gaussian model.