Now when I follow a link in my browser to Youtube, it opens in a new page of my browser, in my case Firefox.
I would have liked that it provokes the launch of another app, for example Minitube, VLC or Totem. This app should then run the desired video. This feature exists already on Android, where Youtube videos can be opened in the Youtube app or in your browser, and this association can be set as you want.
I suppose I could extend this question to other video platforms like Dailymotion, or to other contents, like streaming media, but I will leave it for another question.