Very good add-on. It does exactly what I need, i.e. downloading videos from YouTube. The only drawback at present (March 2019) is that it uses ffmpeg 4.0.1 which does not yet support the AV1 codec. Hopefully, a new release will fill this gap (i.e., it should include ffmpeg 4.0.2 or higher), so that the latest YouTube videos can also be downloaded and assembled properly.