add defaultThumbnail (#3024)
add defaultThumbnail (#3024)


tanyaLibatter/mwEmbed,bordar/mwEmbed,alexmilk/mwEmbed,alexmilk/mwEmbed,tanyaLibatter/mwEmbed,panda-os/mwEmbed,bordar/mwEmbed,bordar/mwEmbed,slash851/mwEmbed,tanyaLibatter/mwEmbed,kaltura/mwEmbed,omridevk/mwEmbed,omridevk/mwEmbed,kaltura/mwEmbed,kaltura/mwEmbed,bordar/mwEmbed,slash851/mwEmbed,panda-os/mwEmbed,omridevk/mwEmbed,FlixMaster/mwEmbed,FlixMaster/mwEmbed,panda-os/mwEmbed,tanyaLibatter/mwEmbed,omridevk/mwEmbed,kaltura/mwEmbed,FlixMaster/mwEmbed,panda-os/mwEmbed,alexmilk/mwEmbed,slash851/mwEmbed,slash851/mwEmbed,FlixMaster/mwEmbed,alexmilk/mwEmbed