Save json_metadata youtube preview image url for iframe embedds. fix #993
Save json_metadata youtube preview image url for iframe embedds. fix #993

steemit/steemit.com,GolosChain/tolstoy,TimCliff/steemit.com,steemit/steemit.com,steemit/steemit.com,TimCliff/steemit.com,GolosChain/tolstoy,TimCliff/steemit.com,GolosChain/tolstoy