This error suggests that the video file you are trying to upload is in a format that Spark Video on web currently does not support. Spark Video on web supports most video files in the .mp4, .mov, and .m4v container formats which are encoded using H.264 video codec, and either MP3 or AAC audio codecs. Other container formats, or codecs are not fully supported. So next step is to convert your video file into a format that Spark Video will recognize.