I don't see much benefit of this for average users, as it's a bit invasive to always force the audio mute for all videos (if the user has no interest in this). Besides, if there is only one user, they could easily turn down/off the audio on the device, or use a browser extension that mutes audio (there are several). In most browsers, there is also an option to disable sound on a per-website basis:
On the other hand, it would not be too complicated to add a
video_mute option, but I would perhaps prefer an automated approach, where Files will "remember" the volume of the audio player. If you mute the first video, following videos will start at volume 0 also ... This would basically allow the volume to remain the same, without having to add clumsy config options.