Compressing 640x64@660 takes exactly the same amount of work as compressing 1280x720@30. You could even use hardware h.264 encoder as long as you can debayer raw 10bit in software fast enough (or convince Broadcom employee 6by9 to make internal Videocore firmware debayering resolution agnostic, its already fast enough keeping up with twice the amount of data when using camera in 1920x1080@25 mode).

But you dont even need fancy compression, at those framerates things change really slowly so simple delta encoding on raw data will do wonders.