FWIW, one of the FFMPEG devs says they "sent a patch for this", 5 weeks ago. In the thread that Roll20 Team linked us to: Andrew Searles said: Hey Folks, I'm Andrew Searles and I'm taking over for Ashton on the VTT team. First, I'd like to say that I'm sorry you haven't heard back from someone on animated webp images for a few months. Second, I'd like to say that we're currently stuck on this. As you have seen, .webp images are supported but animations are still not really. This is because it is not currently supported in one of the libraries that we use. Here is the ticket that we have been watching for them to support this. <a href="https://trac.ffmpeg.org/ticket/4907" rel="nofollow">https://trac.ffmpeg.org/ticket/4907</a> . Once they have support for this, we will add it soon after. Thanks!