449cabcb_asters_______Google_Developers__Required_
[Tag] media:thumbnail [Description] A URL pointing to a preview thumbnail, which must be a GIF, PNG, or JPG image. The preview thumbnail must be hosted on the same domain as the video. [Required?] 
Required
R e q u i r e d
D e p e n d s
O p t i o n a l
Alternate Markups for Videos   |   Webmasters   |   Google Developers