I recently included a .mp4 file on a popup layer in a client's website. The popup renders when the visitor clicks on a logo. Shortly after publishing, Google reported an issue suggesting there was no thumbnail associated with the video. I gather this is desired in case a website visitor can't display videos. I've managed to capture both a .jpg and a .png image of the video, but I'm not sure how to satisfy Google. Would this be a simple link to the url of either of these images? I don't want to do this because currently, clicking anywhere on the page closes the popup, which is my desired effect. Thanks for any advice.