We present ViViD, a variability-based tool to synthesize variants of video sequences. ViViD is developed and used in the context of an industrial project involving consumers and providers of video processing algorithms. The goal is to synthesize synthetic video variants with a wide range of characteristics to then test the algorithms. We describe the key components of ViViD(1) a variability language and an environment to model what can vary within a video sequence; (2) a reasoning back-end to generate relevant testing configurations; (3) a video synthesizer in charge of producing variants of video sequences corresponding to configurations. We show how ViViD can synthesize realistic videos with different characteristics such as luminances, vehicles and persons that cover a diversity of testing scenarios.