Updates translation.

index.html

                         <span id="unreadMessages"></span>
                     </a>
                     <a class="button icon-share-doc" id="toolbar_button_etherpad" data-container="body" data-toggle="popover" data-placement="bottom" content="Shared document" data-i18n="[content]toolbar.etherpad"></a>
-                    <a class="button fa fa-share-alt-square" id="toolbar_button_sharedvideo" data-container="body" data-toggle="popover" data-placement="bottom" content="Shared Video" data-i18n="[content]toolbar.sharedvideo" style="display: none"></a>
+                    <a class="button fa fa-share-alt-square" id="toolbar_button_sharedvideo" data-container="body" data-toggle="popover" data-placement="bottom" content="Share a YouTube video" data-i18n="[content]toolbar.sharedvideo" style="display: none"></a>
                     <a class="button icon-share-desktop" id="toolbar_button_desktopsharing" data-container="body" data-toggle="popover" data-placement="bottom" shortcut="toggleDesktopSharingPopover" content="Share screen" data-i18n="[content]toolbar.sharescreen" style="display: none"></a>
                     <a class="button icon-full-screen" id="toolbar_button_fullScreen" data-container="body" data-toggle="popover" data-placement="bottom" content="Enter / Exit Full Screen" data-i18n="[content]toolbar.fullscreen"></a>
                     <a class="button icon-telephone" id="toolbar_button_sip" data-container="body" data-toggle="popover" data-placement="bottom" content="Call SIP number" data-i18n="[content]toolbar.sip" style="display: none"></a>

lang/main.json

         "invite": "Invite others",
         "chat": "Open / close chat",
         "etherpad": "Shared document",
-        "sharedvideo": "Shared video",
+        "sharedvideo": "Share a YouTube video",
         "sharescreen": "Share screen",
         "fullscreen": "Enter / Exit Full Screen",
         "sip": "Call SIP number",