This one was really nice. Moving it down to the corner makes it worth while chosing a meaningful thumbtime for the video, giving the viewer a hint of what the video is about so that a more informed decision whether or not to start it can be made. Totally obvious it is a video, and hardly no clutter at all. This might be a winner, considering the thumbnails are fairly small in our projects, comparing to embeds of Youtube which seldom is smaller than 400 pixels wide.