Not sure what "mpv" means in this context, but this reminds me the one actual pet peeve I have with Qubes - video/audio calls just don't work for me. It either doesn't work or the audio quality is really poor. I've tried all kinds of stuff, without much success. I'm using phone/tablet as a fallback, but it's not very convenient.
mpv is a free (as in freedom) media player for the command line. It supports a wide variety of media file formats, audio and video codecs, and subtitle types.[0]