Video Thumbnail Plugin featured image add play button when shared

Hi i’d like to add play button to video thumbnail that is generated by video thumbnail plugin. however i did some css and it was working, only to find out that after i shared it on social media sites, the play button disappears because it is not part of the featured image or the thumbnail.

now i want to know how to put play button as part of the video thumbnail not as a separate image.

http://wordpress.org/support/plugin/video-thumbnails