We have a small, new, Omeka install. When installing the YouTube plugin I got this message, though going back to the site the plugin appeared was installed and appeared to be working:
Fatal error: Uncaught Error: Class 'YoutubeImport_ImportHelper' not found in /var/www/stories/plugins/YouTubeImport/YouTubeImportPlugin.php:101
With the YouTube plugin installed and activated, whenever we attempt to view an item, we get this error (though the items can be edited without encountering errors):
Omeka_Record_Exception: There is no element "Item Type Metadata", "Player"! in /var/www/stories/application/models/Mixin/ElementText.php:292
When I deactivate the YouTube plugin the errors don't occur. They re-occur if I reactive the plugin.