Make sure only Videos with tokens are available thru the backend

lib/Models/Videos.php

@@ -264,6 +264,7 @@ protected static function getFilteredVideos($query, $filters)
  }
 
  $where .= " AND trashed = " . $filters->getTrashed();
+ $where .= " AND oc_video.token IS NOT NULL";
 
  $sql .= $where;
 
@@ -789,7 +790,7 @@ public static function addToCoursePlaylist($eventType, $episode, $video)
  // get the courses this series belongs to
  $series = SeminarSeries::findBySeries_id($episode->is_part_of);
  foreach ($series as $s) {
- // Only add video to default playlist if it is not connected to a different playlist in this course
+ // Only add video to default playlist if it is not connected to a any playlist in this course
  $stmt = \DBManager::get()->prepare($sql = 'SELECT count(*) FROM oc_playlist_seminar
  INNER JOIN oc_playlist_video ON (oc_playlist_video.playlist_id = oc_playlist_seminar.playlist_id)
  WHERE oc_playlist_seminar.seminar_id = ?