Open in VLC™ is an Opera add-on that enables you to open desired link(s) in VLC (VideoLAN) application. VLC is a free and open-source media player that can play almost any types of media file (audio or video).
In order to operate with this add-on you need a native-client patch to connect your browser with native VLC application in your OS. When you first install the add-on, please head to the options page and adjust the path for VLC player. Depending on your operating system, the path to VLC could be different. For example, in windows 10 the path is: "C:\Program Files (x86)\VideoLAN\VLC\vlc.exe".
Please re-check this path in your OS and make sure it is correct. Once you set the correct path to VLC in the options page, please install the native-client patch. This patch is used to make the communication between the addon and VLC (native app). Please download and install this patch from (https://github.com/alexmarcoo/open-in-native-client/releases). Follow the instructions in the GitHub page to download and install the related patch to your system. After installing, the "Open in VLC™" add-on in your browser can communicate with VLC media player on your machine (Window, Linux or Mac).
Note 1: please note that Open in VLC™ add-on, does NOT belong or relate to VLC or VideoLAN at all. It is basically an unofficial add-on that is developed and maintained independently by its author.
Note 2: if you want to report bugs or have a feature request, please fill the bug report form in the addon's homepage (https://mybrowseraddon.com/open-in-vlc.html).