www/ajax/events/eventsIndex.php: use media_duration in query

For uniformity. Doesn't change the behaviour.

www/ajax/events/eventsIndex.php

@@ -18,7 +18,7 @@ public function getData()
         $events_portion = 5000;
 
         $query = "SELECT EventsCam.*, Media.size AS media_size, Media.start, Media.end, Devices.device_name, ((Media.size>0 OR Media.end=0) AND Media.filepath!='') AS media_available, ".
-            "IFNULL(TIMESTAMPDIFF(SECOND, Media.start, Media.end), 0) AS video_duration ".
+            "IFNULL(TIMESTAMPDIFF(SECOND, Media.start, Media.end), 0) AS media_duration ".
             "FROM EventsCam ".
             "LEFT JOIN Media ON (EventsCam.media_id=Media.id) ".
             "LEFT JOIN Devices ON (EventsCam.device_id=Devices.id) ".
@@ -125,7 +125,7 @@ public function getData()
                     $entry['content'] = array(
                         'media_id' => $item['media_id'],
                         'media_size' => $item['media_size'],
-                        'media_duration' => $item['video_duration'],
+                        'media_duration' => $item['media_duration'],
                         'content' => (!empty($_SERVER['HTTPS']) ? 'https' : 'http') . '://' . $_SERVER['HTTP_HOST'] . '/media/request.php?id=' . $item['media_id']
                     );
                 }