Please Read this Information before you add Media !

YouTube Links :

You have to add the share link of a youtube Videolink. Get it from the Adressline of your Browser !

Original Link :
http://youtube.com/watch?v=Dt-yQzETFDM&feature=dir

Cut the ending (&feature=dir) :
http://youtube.com/watch?v=Dt-yQzETFDM

If you add the Link like the example above then you don´t have to add the thumbnail link, it will be generated automatic !

PS: You can add the Original link too, but then you have to add the Thumbnail link otherwise the video will shown but the Preview Image Thumbnail not!