Parfait!
sudo nano ~/.local/share/applications/mimeapps.list
[Added Associations]
video/mpeg=vlc.desktop;
inode/directory=nautilus-folder-handler.desktop;[b]vlc.desktop[/b];nautilus-browser.desktop
video/x-msvideo=vlc.desktop;
application/x-extension-CHK=vlc.desktop;
application/x-ms-dos-executable=wine.desktop;
application/x-java-archive=file-roller.desktop;openjdk-6-java.desktop;openjdk-6$
video/x-ms-wmv=vlc.desktop;
video/x-flv=vlc.desktop;
video/mp4=vlc.desktop;
text/html=firefox.desktop;google-chrome.desktop;wine-extension-html.desktop;win$
text/plain=gedit.desktop;wine-extension-txt.desktop;openoffice.org-writer.deskt$
application/x-php=gedit.desktop;wine-extension-txt.desktop;openoffice.org-write$
application/octet-stream=gedit.desktop;
video/x-matroska=vlc.desktop;
application/x-bittorrent=azureus.desktop;
video/quicktime=vlc.desktop;
J'ai donc supprimé le vlc.desktop
Et tout fonctionne pour le mieux.
Merci pour ta diligente réponse!