Welcome to the forums, thanks for starting a new topic and enjoy Vivaldi Browser.

type vivaldi://version on the Address Bar to get the full path of the Profile folder HTML5 is present on your machine, YT requires it access to content protected by DRM - in https://demo.castlabs.com there is a video that includes subtitles HBO, Netflix have a look at this article available on Vivaldi Browser Help (hit F1 to access). @ruario (our Linux Wizard) is the author of many of those shell scripts.