The codec was interfering with a certain website and that prevented Firefox from playing videos on that particular website.
This error occurs because the user has a corrupted codec installed on one of his devices.
Video File Cannot Be Played (Error 102630) Why this happens is not something that can be answered in a single sentence, so listed out below is a detailed explanation of these problems which users like you may have experienced at one time or another. These errors disrupt video playback or even outright prevent the videos from playing. Mozilla Firefox is a very utilitarian web browser but users around the world have attested to how errors can plaque it. Part 1: Different Errors Showing Firefox Won't Play Videos