Looks like you already have inserted the vimeo video. To hide the image, you can use the following hack for now.
Input the following in the Custom CSS tab of options panel –
body.postid-2066 .image-container.full {
display:none;
}
where 2066 happens to be the post id for the video post. You can view the source of the post to see the post id.
Actually I have made changes to the theme to take care of this automatically for portfolio posts (not blog posts though) and the update is expected in next week or so.