Currently "Video Thumbnails" is limited by the number of web sites it is coded to work with. But adding oEmbed support instead would make it easy to use "Video Thumbnails" in ways it was never intended to be used. (I would love to be able to pull thumbnails from SoundCloud tracks.) I'm not a programmer, so I'm not clear on the specifics, but from what I understand, this should be doable...in fact it's the whole reason the oEmbed standard exists.
I really hope you'll look into this. Any thoughts?