Getting rids of blank slide at beginning of videos

On our upcoming disability website we host a number of videos by other people.  The way our new video previewer works is it takes the first frame of videos and uses that as the image on the webpage.  However a number of them have gray screens or are blank and give us an awful look.  IS there a way to correct this so our videos which are linked  to other peoples and youtube videos can have an image instaed of a gray screen?  See example