Congratulations, you just upgraded to Video DownloadHelper 6.3.1 for Firefox You may have noticed that for some time, downloaded videos from Vimeo (or from sites hosting their videos on Vimeo) do not have audio. This is due a change in their streaming technology and they now stream the audio and video parts of the media separately, as YouTube have been doing for several years. The Video DownloadHelper workaround is the same as with YouTube: use an external video converter to aggregate audio and video streams into a single audio+video file that can be used by your video player. We are aware of the inconvenience of having to install an external application, but there is no easy alternative here. Note that once the converter is installed, the process is totally transparent and you end up with a fully playable video without any special action. If you want to avoid using the converter, you can still use Video DownloadHelper to download separately the two streams (but you will have to find a way to play them together). For doing so, open DownloadHelper settings > More > Chunked streaming, check Advanced. In section DASH streaming, parameter When DASH contains both audio and video lets you choose which stream(s) you want to download. Default is Aggregate audio and video, which implies using the converter but you can change it to choose audio or video only.