In computer vision, all we do depend on the photos or video material we analyse. It guides even the most powerful neural network that encodes the largest amount of prior knowledge. In this talk, I will shed some light on how illumination, movement, camera specifications, and video encoding affects the video quality. My students have quantified the VIIDEO score for our Parkinson's disease and rPPG datasets, which we use to track skin features and quantify the heart rate.