Try changing the URL to something like this:
"https://i.vimeocdn.com/video/742943172_800x450.jpg?r=pad"
The "800x450" is the desired image size. You can pretty much use anything that you want, but I think Direct Publisher prefers 800x450.
The "?r=pad" is optional. If present it will pad the image on the left+right or top+bottom with black bars instead of cropping to fit the specified size.
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